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by Paul Haynes
Header image by Barry McGill.
Header image: Deep wreck diver Gareth O’Neill giving scale to one of the impressive 13.5″ gun barrels on the wreck of the King George V-class dreadnought battleship HMS Audacious, which lies in 64m (210 ft.) off the coast of North Donegal, Ireland.
The paper was first published in the Diving and Hyperbaric Medicine Volume 46 No. 4 December 2016 253
When compared to open circuit scuba, it is acknowledged within sport, military and occupational diving organisations that the probability of exposure to an inappropriate breathing gas is increased when using rebreathers. 1
As a result, a serious or fatal incident is more likely when rebreather diving. 2
Inappropriate breathing gas scenarios most frequently associated with rebreather use are: (1) hypoxia; resulting from respiring an hypoxic gas, (2) hypercapnia, resulting from increased levels of inspired carbon dioxide (CO2), or hypoventilation, (3) hyperoxia, resulting from respiring an hyperoxic gas. 3
The sport diving community, defined here as manufacturers, diver training agencies, instructional cadre, and divers, frequently refers to these maladies as the rebreather ‘3H hazards’, all of which can lead to loss of consciousness (LoC) with little or no warning.
The most common interface between the rebreather and the diver’s respiratory system is a mouthpiece valve assembly, frequently called a dive surface valve. This human-machine interface is referred to in this paper as a “mouthpiece” and is used in conjunction with a sport diving “half-mask.” The mouthpiece typically requires manual operation by the diver to change from “surface mode,” which isolates the rebreather re-circulation system (breathing loop) from the environment, to ‘dive mode’, which allows access to the breathing loop and breathing gas.
As tone is lost from the mandibular muscles following LoC, the likely consequence is loss of airway protection as the mouthpiece/breathing loop falls from the mouth of the diver. If this occurs underwater, unless there is immediate intervention by a diving partner, the following outcomes are highly likely: (1) fluid aspiration and asphyxiation, (2) venting of breathing loop gas via the open mouthpiece, (3) whole or partial flooding of the breathing loop, (4) loss of buoyancy, (5) drowning.
Although other factors (triggers) are inevitably responsible for initiating the accident, loss of airway protection and subsequent drowning is most frequently the actual cause of death (CoD). This paper examines a potential means of delaying or limiting this cycle, thus increasing the probability of surviving LoC underwater when using a rebreather.
The mid-1990s saw the beginning of an upsurge in the use of rebreathers by sports divers. At that time, the sport diving industry had limited rebreather experience and so in anticipation of a growth in rebreather popularity, in 1996 the diving industry organised Rebreather Forum Two (RF2). The conference was organised to address the major issues involved in bringing rebreather technology to the consumer market-place and was divided into working sessions to identify the key technology, safety, training, and risk management issues. Drawing on the collective experience of numerous delegates from sport, military, and occupation diving backgrounds, a consensus was developed in order to help shape future sport rebreather diving practice.4
Rebreather Fatality Analysis
As anticipated, sport rebreather use increased post RF2. Subsequently, with consideration to the relatively low number of rebreather sport divers, there appeared to be a disproportionately higher number of reported rebreather fatalities when compared to open-circuit scuba. As a consequence, Divers Alert Network (DAN) conducted a study comparing sport diving open circuit and rebreather scuba fatalities from the period 1998 to 2006.5 Due to the difficulty in attaining comprehensive rebreather accident data specific to each fatality, in particular CoD as determined by a Medical Examiner (Coroner), the DAN study was restricted to a low number of rebreather fatalities (80 cases). However, study conclusions appeared to support the following related 1996 RF2 consensus points:
“Rebreathers are much more complex than open circuit with insidious risk.”
The 2007 DAN analysis concluded that, of the cases studied, equipment trouble (human error or technical failure) was the trigger (something that turns an uneventful dive into an emergency) in over 40% of rebreather fatalities compared to just over 15% of open circuit fatalities (Figure 1). In addition, inappropriate breathing gas (insidious risk) was the disabling injury (something that causes death or makes drowning likely) in over 50% of rebreather cases compared to less than 5% of open circuit cases (Figure 2).
“Loss of consciousness presents a significant hazard when using rebreathers, likely to result in death by drowning.”
The 2007 DAN analysis concluded that in 94% of cases studied, the actual CoD, as determined by a Medical Examiner, was drowning (Figure 3).
In an effort to quantify rebreather diving risk, in 2013, a separate rebreather fatality study concluded that of the 181 cases analysed between 1998 – 2010, study data suggested a four- to ten-fold increased risk of death when rebreather diving compared to open circuit scuba diving2. The study also reported that a rebreather potentially has a 25-fold increased risk of component failure compared to an open circuit manifolded twin-cylinder scuba system. This study therefore also appears to further support the RF2 consensus statements discussed above.
An incident is defined here as an unplanned event that degrades safety and culminates in equipment damage, diver injury, or death. Rebreathers are complex equipment that form one element of a broader life support system that includes: (1) the diver (attitude, skill set, knowledge, experience, health and fitness to dive), (2) dive partner / team (attitude, skill set, knowledge, experience, health and fitness to dive), (3) surface support team (attitude, skill set, knowledge, experience, emergency response protocols, emergency medical facilities), (4) diving ancillary equipment (functionality and fitness for purpose), (5) environmental protection equipment (functionality and fitness for purpose), (6) procedural/diving methodology (appropriateness and fitness for purpose).
Rebreather incident data suggests that a frequent contributing factor is knowingly or unknowingly violating diving and/or equipment protocols as opposed to equipment malfunction.2 This is in keeping with data from the marine oil and gas industry where approximately 80% of incidents investigated were related to human unreliability, and approximately 20% were related to technical causes.6 These figures support a widely held perception amongst the sport rebreather community that the diver is the “weak link” in the life support system “chain” described above.
To assist in the estimation and qualification of human error, Swain and Guttman developed a generic rate from experiment and simulation in the operation of nuclear power plants (Figure 4).7 If we consider an experienced rebreather diver in a benign environment, the assembly, testing, pre-dive donning and functionality confirmation (pre-breathe) procedures, all of which are essential to safe rebreather use, could be considered to fall into the fourth row of Figure 4, i.e., difficult but familiar task, little stress, sufficient time, very little distractions or impairments. The mean probability of human error or failure per task for such a scenario is between one in 1,000 events to one in 10,000 events. Thus, even under relatively benign conditions, experienced divers will occasionally make errors. It may be concluded, therefore, that to a lesser or greater extent, all levels of rebreather diver from novice to expert are prone to human error, the consequence of which could be exposure to an inappropriate breathing gas and LoC underwater.
Rebreather Accident Prevention
To help prevent rebreather diving accidents the following key measures are presently implemented or recommended by sport diving training agencies and equipment manufacturers:
- Use of equipment that has been subject to independent third party testing against a recognised international standard
- Appropriate training standards and their strict application by diving instructors
- Appropriate dive planning
- Analysis and clear labelling of all gas cylinders
- Use of assembly and test checklists
- Remaining within manufacturer’s recommendation / performance guidelines
- Remaining within training qualification parameters
- Pre-breathe and function check prior to entering the water
- Diving in pairs/teams
- Frequent oxygen partial pressure display monitoring
- Remaining within appropriate dive planning parameters
- Application of appropriate preventive and corrective maintenance
These incident mitigation measures are also applied within military and occupational diving environments, often to a greater level of detail and enforcement.8, 9 However, despite what is often the rigorous application of equipment maintenance schedules, prescriptive diver supervision, and organisational management systems, in the author’s experience, human error remains a common characteristic of military and occupational rebreather diving incidents. Therefore, within the sport diving environment, it is reasonable to assume that, as a consequence of less formal diving equipment maintenance schedules, supervision, and management practices, human error will likely continue to remain a common characteristic of sport rebreather diving incidents with the resulting potential for LoC.
Aspiration of as little as 1–3 ml∙kg-1 [0.02-0.05 oz/Ibs] per body weight of water produces profound alterations in human pulmonary gas exchange.10 It is also reported that average water aspiration in drowning is relatively small, rarely exceeding approximately 2.2 ml∙kg-1 [0.03 oz/Ibs] per body weight.11
Therefore, preventing or limiting fluid aspiration following LoC underwater is critical to surviving such an event. Whilst it is acknowledged that the diver may eventually die as a consequence of exposure to an inappropriate breathing gas, this can take a number of minutes or longer depending upon the breathing gas composition and ambient pressure (depth). If water aspiration is prevented or delayed following LoC, a diving partner may be able to affect a successful rescue. Alternatively it is conceivable that under certain circumstances, the distressed diver may regain consciousness, potentially enabling self-rescue.
To mitigate fluid aspiration following LoC underwater, a 1996 RF2 consensus statement endorsed the use of the full-face mask (FFM). However, a FFM adds to equipment complexity, and restricts access to alternative breathing gas supply systems whilst increasing maintenance, training requirements and associated cost. These factors likely account for the sport rebreather diving community having not embraced the widespread use of FFMs despite their potential safety benefits.
One occupational diving equipment manufacturer has developed an innovative hybrid FFM/half mask design.12 This mask system enables the ready separation of the lower oral section of the mask, which incorporates the rebreather mouthpiece. This design offers FFM airway protection benefits whilst also facilitating ready access to alternative breathing gas delivery systems. However, the sale of this hybrid design has generally been confined to government and occupational diving organisations. This and the relatively high cost appear to have restricted its wider use by sport rebreather divers.
In recognition of the possibility of encountering inappropriate breathing gas and the associated potential for LoC underwater, when a FFM is not used, the mouthpiece retaining strap (MRS), combined with related training, has been employed by militaries worldwide for over half a century. It is a common safety design feature of the vast majority of both classic and contemporary military rebreather designs where the manufacturer has endeavoured to provide airway protection in the event of LoC underwater. In its simplest form the MRS is an elasticated adjustable strap secured to the breathing loop/mouthpiece. To optimise its effectiveness, the MRS is worn over the crown of the head and adjusted to positively hold the mouthpiece in position without causing undue discomfort. More sophisticated versions incorporate a padded flange. When retracted around the face by the distended strap, the padded flange enhances the lip seal whilst also helping to secure the mouthpiece in position (Figure 5). The MRS is a relatively low cost, simple and available alternative to the FFM.
Mouthpiece Retaining Strap Efficacy
A literature search has failed to identify any formal evaluation of MRS efficacy. The subject was discussed at Rebreather Forum Three (RF3), Orlando, Florida, in May 2012, and a RF3 consensus statement reads: “The forum identifies as a research question the issue of whether a mouthpiece retaining strap would provide protection of the airway in an unconscious rebreather diver.”13 However, it is unlikely that a meaningful prospective experimental evaluation of the MRS could be undertaken in human subjects. In the absence of a specific formal study, the suggestion of MRS efficacy is principally based upon observational (anecdotal) evidence from military diving sources.
As a measure of the perceived potential effectiveness of the oral seal achieved by a correctly worn MRS, when conducting a diver rescue, some closed circuit oxygen rebreather military user groups are trained to break the MRS oral seal by partially inserting a finger under the unconscious diver’s lip at the corner of the mouth. This is believed to help facilitate the venting of expanding gas from the distressed diver’s lungs and reduce the risk of pulmonary barotrauma on ascent.14 Military groups who train this technique believe that an appropriately designed MRS results in an effective seal between mouth and breathing loop mouthpiece. Anecdotal evidence from various experienced military rebreather divers/diving supervisors, including the author, suggest that the use of a MRS has on various occasions been a key contributory factor to surviving LoC underwater. It is also the author’s experience as a passenger in a free-flooding combat submersible swimmer delivery vehicle, that whilst in an upright fetal position, the MRS has provided airway protection during periods of sleep lasting up to 10 minutes.
These perceptions are corroborated by one notable study that analysed 153 accidents amongst French military rebreather divers.15 Fifty-four of these events led to LoC underwater; however, this resulted in drowning in only three cases. The military report states: “gas toxicities are frequently encountered by French military divers using rebreathers, but the very low incidence of fatalities in over 30 years can be explained by the strict application of safety diving procedures.” These procedures include:
“Systematic linking of divers in pairs, so that a diver can find his buddy regardless of diving conditions (particularly if visibility is poor) and can lend assistance in the event of rescue”.
“Using a strap to hold the mouthpiece in position, along with a lip guard, so that an unconscious diver can still breathe without risk of drowning. The rescuer can then concentrate on the quality of assistance and respecting the diving parameters for regaining the surface”.
The report gives no weighting to either of these factors, so it is unclear which, if any, played a larger role in preventing drowning in 51 out of the 54 LoC events. However, protecting the airway from water aspiration and effecting rescue at the earliest opportunity are cited as key factors to surviving LoC underwater. The related benefit implied by this military diving study is likely to be translatable to the sport diving setting.
Rebreather Solo Diving?
Of the 80 rebreather fatalities reviewed in the 2007 DAN study, 33% (26 cases) involved solo diving as a result of either deliberately diving alone or becoming separated from a diving partner. In support of this finding, whilst its accuracy cannot be readily verified, a publically available on-line collation of sport rebreather fatalities suggests that solo diving continues to remain a prominent characteristic of sport rebreather deaths that have occurred since 2007.16 Due to the increased probability of respiring an inappropriate breathing gas when using a rebreather and the absence of a dive partner to witness early signs of diver distress or performance impairment and to implement rescue, solo rebreather diving appears to present additional risk.
Even a well-designed and correctly fitted MRS is unlikely to provide airway protection over an extended period following LoC. Therefore, to realise any safety benefit accruing from delaying or preventing drowning, the maintenance of close contact with a dive partner is also considered an important component to surviving LoC underwater. This proposition appears to be supported by the French military study, in which divers have survived LoC as a result of MRS use and early rescue by a dive partner.
Sport Rebreather Design And Performance Standards
European standard EN14143:2013 sets minimum design and performance parameters for sport rebreathers sold within the European Union, where compliance is a mandatory aspect of consumer law.17 It is also setting a broader global benchmark for rebreather design standards. However, human error and equipment failure will likely remain a characteristic of sport rebreather use. It follows that the provision of airway protection is a desirable safety design feature regardless of rebreather performance and reliability. Indeed, EN14143:2013 specifies a design requirement regarding a ‘face-piece’, which the standard defines as: “a mouthpiece assembly, a half mask, a full-face mask or a helmet”. The standard goes on to state: “The face-piece shall aid ear clearing by allowing the diver’s nasal passages to be occluded. It shall also minimise the ingress of water during normal use and in the event of a diver falling unconscious or having a convulsion.”
Whilst it is not specified how the minimisation of water ingress is to be implemented, EN14143:2013 states: “The face-piece harness shall be designed so that the face-piece can be donned and removed easily. It shall be adjustable or self-adjusting and shall hold the face-piece assembly firmly and comfortably in position.” The standard subsequently defines the design and functional requirements of a retaining strap, if fitted.
The European rebreather standard therefore recognises the potential safety benefit of protecting the airway and breathing loop in the event of LoC and as a consequence incorporated the requirement into its design specification (Anthony G, personal communication, 2014; principal author of ENI4143:2013).
To extend the exploration parameters of self-contained sport and scientific diving to date, relatively small groups of “technical divers” have been the most prevalent users of rebreathers. However, a considerably larger sales potential is thought to exist amongst mainstream sport divers. As a consequence, considerable resource is presently being applied by the sport diving industry to introduce rebreathers into this larger market place.18, 19
To help facilitate mainstream rebreather diving, the world’s largest recreational diving training agency has defined a generic recreational closed circuit rebreather (rCCR) specification and developed what it considers to be appropriate rCCR training standards. As a consequence, manufacturers are either producing dedicated rCCR models or adapting previous rebreather designs to comply with this rCCR specification.20, 21 Rebreather use will likely continue to increase amongst sport divers.
A mandatory rCCR specification safety feature is the bail out valve (BOV) (Figure 6). In an emergency, it enables the diver to manually access a source of open-circuit breathing gas without the need to remove the mouthpiece. However, it is worth noting that the MRS is not a mandatory rCCR safety feature. Despite the EN14143:2013 design requirement previously discussed, the reason for this remains unclear but may result from the fact that the MRS has historically not formed part of sport rebreather design. Therefore, awareness and experience of its application and potential safety benefit is limited amongst the sport rebreather community. In addition, whereas a BOV is increasingly an integral part of sport rebreather design, contrary to EN14143:2013, it continues to remain the norm for the vast majority of manufacturers to sell sport rebreathers without “a means to minimise the ingress of water in the event of a diver falling unconscious” or a means to “hold the face-piece assembly firmly and comfortably in position.”17
Airway Protection Spectrum
We may consider the upper end of the airway protection safety ‘spectrum’ is an occupational diving helmet interfaced with a rebreather. An example is the Secondary Life Support saturation diving emergency bailout rebreather manufactured by Divex.22 Assuming the watertight integrity of the breathing loop and helmet, water aspiration and, therefore, drowning following LoC, is highly improbable. At the low end of this ‘spectrum’ is the absence of any means of protecting the airway following LoC. Despite acknowledging the increased potential for exposure to an inappropriate breathing gas and LoC when rebreather diving, the sport diving community largely remains posiioned at the low end of this “spectrum.”
Rebreathers incorporate a high number of inherent failure modes and the potential for human error. Individually or in combination this can lead to inappropriate breathing gas and spontaneous LoC underwater. If the airway is unprotected, water aspiration and asphyxiation is the likely immediate outcome. Whilst FFMs are considered to offer a high level of airway protection, due to cost and complexity they are unlikely to be widely adopted by sport rebreather divers.
Military rebreather manufacturers consider the MRS a safety-critical design feature, which is extensively employed throughout the global military rebreather diving community. Observational evidence suggests the correct use of a MRS can be an effective means of preventing or limiting water aspiration immediately following LoC. This potentially extends the window of opportunity for effective rescue or conceivably, self-rescue should consciousness be regained.
In the vast majority of sport rebreather fatalities, drowning is the actual cause of death. Therefore to directly mitigate the immediate consequences of loss of airway protection following LoC underwater, an effective MRS should be a standard component of all rebreathers used by sport divers. In addition, in order to raise awareness of the potential safety benefits, its use should be mandated within sport rebreather training standards.
3. Doolette DJ, Mitchell SJ. Hyperbaric conditions.Comprehensive Physiol. 2011;1:163-201.
4. Richardson D, Menduno M, editors. Rebreather Forum2 Proceedings. Redondo Beach, CA: Diving Science and Technology; 1996.
5. Vann RD, Pollock NW, Denoble MD. Rebreather fatality investigation. In: Pollock NW, Godfrey JM, editors. Diving for science 2007. Proceedings of the American Academy of Underwater Sciences 26th Symposium. Dauphin Island, AL: AAUS; 2007.
6. Bea RG, Roberts KH. Human and organisational factors in design, construction and operations of offshore platforms. Offshore Technology Conference. Houston, TX. 1995.
14. Royal Australian Navy Diving Manual. ABR 155. 2005 Vol2. Rev 2. Ch 12. Para 12-70.
15. Gempp E, Louge P, Blatteau JE, Hugon M. Descriptive epidemiology of 153 diving injuries with rebreathers among French military divers from 1979 to 2009. Mil Med. 2011;176:446-50.
17. European standard EN14143: 2013. Respiratory equipment- self-contained re-breathing diving apparatus. European Committee for Standardisation. Para 5.10. 2013.
20. Menduno M. The future of diving. Diver Magazine. 2011;37(3):18-25.
21. Menduno M. Rise of the recreational rebreather. Diver Magazine. 2011;38(8):18-25.
Paul Haynes is a former UK Special Forces (SF), Special Boat Service (SBS) Combatant Diver Instructor, Diving Supervisor and Swimmer Delivery Vehicle (SDV) Operator. Upon leaving UKSF, he worked for Divex Ltd (now JFD) the world’s largest manufacturer of professional diving equipment. As a result, Paul has remained at the forefront of defense underwater life support systems research, development, design, test and training for over two decades.
Paul is a RAID advanced mixed gas diving and rebreather Instructor Trainer, as well as a PSAI and BSAC instructor, and has authored several rebreather training manuals and numerous safety related articles for civilian diving publications. He has been an invited keynote speaker at numerous technical diving conferences to discuss rebreather development, safety and training, and has provided civilian rebreather accident investigation assistance to U.S. law enforcement. He provides consulting services through his firm Haynes Marine Ltd.
Paul is a prolific shipwreck explorer and has participated in the discovery of numerous deep shipwrecks in the North Sea off the East coast of Scotland, and is a member of the Explorers Club of New York. In addition, he has been the diving safety officer on a number of high profile diving expeditions including UK Ministry of Defence sanctioned 2016 survey of HMS Hampshire, and the joint UK Royal Navy/civilian expedition to recover of the bell from the Battleship HMS Prince of Wales sunk during WWII in the South China Sea.
One Way The World Learns to Mermaid: The Mer-spective from PADI’s Karl Shreeves
InDepth’s editor-in-chief Michael Menduno reached out to PADI veteran Karl Shreeves to explore the trending global phenomena of mermaiding….
by Michael Menduno
Header image and photos courtesy of PADI Inc. unless noted.
InDepth’s editor-in-chief Michael Menduno reached out to PADI veteran Karl Shreeves to explore the trending global phenomena of mermaiding, which may well surpass tech diving in terms of sheer numbers in the not so distant future! While you shouldn’t expect to see a Global Underwater Explorers (GUE) “MER 1” class anytime soon, it’s fair to say that mermaiding is here to stay—and that’s arguably a good thing. Here’s why!
As a uniquely dominant force in the $2-3 billion worldwide sport diving market, with nearly 6600 affiliated dive centers and resorts and over 128,000 members, it’s not surprising that privately-held PADI Inc., the self-proclaimed, “Way The World Learns To Dive,” is one of the most closely watched and talked about companies in the business.
Over the last thirty years, since the emergence of technical diving, PADI has arguably relied on others—“Brand X” in PADI parlance— to bring technological innovation to the diving market while keeping a careful eye on their progress. Once a sufficient market develops, PADI moves in to adopt, standardize, promote, and profit from the innovation, and help popularize and fuel its growth by virtue of PADI’s sheer scale, often to the dismay of competitors. It’s a tried and true model that the organization has applied to nitrox, open-circuit tech diving, recreational rebreathers, and recently even freediving.
So, it was perhaps inevitable, given the tremendous growth and interest in mermaiding over the last decade, along with the entry into the market by Scuba Schools International (SSI) and NAUI, that PADI would pick up the tail, err trail, and offer its own mermaid program aimed at aquatic consumers, and its own teeming instructor ranks. Τhe fifty-five year old training behemoth launched the program in December 2020 and kicked it into high gear last April, with a TikTok-savvy, mono-a-mono, Guinness World Record extravaganza —the largest mermaid show on Earth—held at the Atlantis Sanya hotel aquarium, in Sanya China. Cirque du Soleil move over!
Accordingly, to get a perspective on the market, we reached out to PADI’s original tekkie, technical development executive Karl Shreeves, who helped field its mermaid program, and was instrumental in the development of PADI’s nitrox and tech diving courses. Here’s what the veteran educator had to say.
InDepth: To start, let me ask you: How did PADI get involved in mermaiding? When did you start looking at it and thinking about creating a training program?
Karl Shreeves: PADI had actually gotten involved with mermaiding several years ago. We had several instructors who had become part of the existing mermaiding community that wanted to offer a distinctive specialty. So, they submitted the distinctive specialties outlines, and we approved them. And then it started to grow, and the interest started to grow, and we began to get calls for us to create a program like we have for freediving and scuba diving and other types of diving.
So, we started developing that in 2018 into early 2019. At the time, for us, and by us, I mean what was then the mainstream diving community apart from mermaiding, it was pretty small potatoes. Mermaiding already existed. It popped up on its own track separately from diving. There were already mermaiding schools and people doing it who did not come from a diving background at all. They just got into mermaiding.
Did things slow down with the pandemic?
On the contrary. The interesting thing was that the pandemic seemed to propel it. And the reason? What do water enthusiasts do when they can’t travel? They get into the local pool. The pandemic helped freediving as well, and in some areas, local diving did well. Scuba divers quickly figured out that, “Well, I can’t see as far in my local lake as I can in Grand Cayman, but it’s actually pretty cool.” They get a trained eye and a perspective.
But as the pandemic forced us to stay closer to home, there was a growing interest among the traditional diving community in this form of diving because, unlike freediving and scuba diving, all of a sudden, there was an expressive form of diving. It’s underwater dance. The costumes are beautiful. Obviously, it borrows from other kinds of diving. They all borrow from each other, right?
But you know, especially if you were going to be primarily in a pool, it gave water enthusiasts a new craft that is well suited to the swimming pool. While there is open water mermaiding, as you know, a lot of it is purely in a swimming pool or the various dedicated super pools, and it’s a really good fit there. So mermaiding is a new angle, if you will, for expressing yourself.
It’s a performance art in many ways, like synchronized swimming or water ballet.
Right. Of course, there are a lot of people who come from the diving side and they say, “Well, it’s a form of freediving.” But really, it’s not.” It shares a lot from freediving. It has borrowed a lot from free diving, but it’s really different.
Freediving tends to be more about the performance of depth and duration. It’s an athletic accomplishment. And again, there’s overlap. I’m speaking a bit in absolutes, but don’t misunderstand me. Mermaiding is more about individual expression and fantasy made real—an ability to touch people in a way that goes as far as wearing make-up as well as some elaborate costumes. And yet, having to be able to swim. And not just swim, but to look elegant and interact with people.
That’s where it’s got an appeal because that hasn’t previously existed much in diving. Probably the closest thing would be being an underwater model. Ironically, because of the pandemic, and lock-downs, I wasn’t able to be one of the shooters for our Mermaid eLearning course. If there was ever a shoot I wanted to do it was that one!
Ha! You were deprived! What about the language? You use ‘mermaid’ to refer to both genders, not mermaids and mermen, or merfolk?
Funny you ask about “mermaid” as a term, because we actually explain it at the beginning of the course. “Mermaid” denotes gender in English, but in many languages the translated term means “human fish” and doesn’t indicate gender unless you add words to do so. Some in mermaiding use the terms “merfolk” and “merman” etc., but broadly, “mermaid” is the term everyone knows. So, the PADI materials use “mermaid” in the sense of “human fish” as in languages like Chinese, Japanese, Korean, and Vietnamese. But obviously, it’s not a female-only sport by a long shot. Lots of men are mermaid divers and PADI Mermaid Instructors.
I’m sure some of our readers see mermaiding as a trend, something new, but the concept and fascination with mermaids goes back a long way.
It’s not new. It goes back over 1,000 years. There is something about this idea of a human fish that has endured. If you look at the movie Splash, right? 1984. The sixth largest grossing movie in China was The Mermaid. And they are talking about a sequel now. The Korean drama I keep talking about, Legend of the Blue Sea, is one of the most successful dramas they’ve had. Very popular, and people still watch it aftermarket and buy it on DVD. So, this is not a flash in the pan. It’s actually a cross-cultural mythology that we’ve enjoyed as humans. If it were just one culture you’d say, eh… But it’s not.
Every culture independently created this myth. Now the modern mermaid tends to be the European mermaid, and we talk about this in the course too. Why? Because it’s practical. The European mermaid’s bottom half is fish and top half is human. Very easy to create a swimmable costume. But some, you can do it with computer graphics, it’s a fish with a human face. But my point is that when we look at this as the dive community and say, “Oh, that’s just a bunch of people playing around.” Yeah, it is, but that’s not new. This has been around. So this is going to stay. Now that we have the ability for people to go play mermaid in a serious, fun way, they are going to keep doing it because it’s cool.
In some ways, it enables us to reach back through time and connect with this myth that’s embedded deep in the human psyche.
Once humanity starts to picture something, we find ways of making it happen. And that’s what’s happened to the thousand-year-old dream of being a human who can live in water. We found a way to make it real.
Talk to me a little about the size of the market. Obviously if PADI is getting into it, you must think there is sizable potential. I was surprised when I attended the ADEX show in Singapore in 2019, and they had a huge mermaid section. In fact, it was bigger than the tech diving section! They had 30 or 40 famous mermaids there. I didn’t know who they were, but the people knew them and cheered for them. It was amazing.
Well, as I said, parts of the dive community had adopted mermaiding. It was already growing globally. In fact, it’s really big in Asia in terms of its visibility, but there’s actually a pretty strong community around the world. There are communities in Europe. Here in California, they have a small mermaid convention that’s been held for several years in the Bay Area. It’s not huge but it’s there, and quite separate from diving. It’s about mermaids and mermaiding. They get in the water; they talk about mermaid stories and myths. They role play, and there’s also a little bit of cosplay. Ι think that is part of the fun for some people.
But to give you an idea of scale, when we finally launched the full version of the program within, I want to say, it was a month or two months, we had 500 instructors.
Wow. That’s surprising! Evidently there’s a lot of pent up demand.
Right? When you pick up that many instructors that fast, it’s two things. One, it is popular. Two, it’s already widespread because you don’t learn to mermaid and then reach instructor qualification in two months. You actually have to already have the qualifications. And what we’re seeing is two prongs of appeal.
First, it’s opened the eyes of divers who’ve never looked at it before and are most certainly going, “That’s cool.” A lot of them are free divers, but some of them are scuba divers. They’re like, “I want to give that a go.” But then we are also seeing that it’s pulling from the original market—people just interested in mermaids who want to live out the fantasy, as it were. That gives it a lot of youth appeal, especially among younger children.
What we’re finding is that attraction is growing because some of these people realize that it also brings them a connection to diving. It’s like, “I’m not only going to become a mermaid, but, if I want, I can grow towards becoming a diver as well.” Some people find that out in the course. Because, as you might expect, a lot of the mermaid instructors also have their fins in the freediving camp. Those people tend to do a really good job of instructing because they know the difference. They know the difference between mermaiding and freediving. So, they don’t try to make mermaid divers freedivers, but they do train the mermaids in the techniques that apply from one to the other.
In fact, somebody was asking me about this. “Oh, it’s just a form of freediving.” And I said, “No, not really.” However, when you are a buddy, that is the safety diver in mermaiding, that’s when you’re closest to being a freediver because basically you have the same job.
Makes sense. Freediving has developed safety techniques and protocols, which I would imagine apply to mermaiding too, so that mermaids don’t blackout underwater?
Yeah, in fact mermaiding basically borrowed that most directly. So, while mermaids don’t do static apnea, they swim dynamically as free divers call it. In other words, there’s lots of horizontal movement, but depth isn’t too great. Of course, the more experienced ones still get down there pretty well. But as soon as you shift—”Okay, it’s my turn to be the buddy.”—the mermaid tail comes off, the mask goes on (which is optional if you’re the mermaid), and you wear bi-fins because you need to be able to help and maneuver quickly in the event of a problem. So, that’s probably where you have the most and the strongest connection to conventional freediving.
Mermaids wear monofins but they use bi-fins when being a safety?
Right. They are required to use bi-fins for safety because they need to be fast and maneuverable as a safety. But by definition, if you’re a mermaid, what kind of fin are you going to have? I suppose somebody might come up with a bi-fin mermaid look, but basically, it’s all monofin. They’re going to learn both to be successful in the course.
In freediving, they have the one up, one down system, or one up, one prepping, one down in a team of three, in order to rescue the diver in case of hypoxia. So, mermaids also have somebody watching them who is ready to intervene when they’re holding their breath underwater?
Exactly! Freediving has done a lot for all breath-hold diving, just like tech contributed to all scuba diving. Tech taught us to be tighter with teams and also offered a mindset and approach that has been picked up. The alternate air source originally came from tech. Likewise, freediving has influenced breath-hold diving, even basic snorkeling. Divers are taught that they have to take the snorkel out of their mouth when you’re doing a breath-hold dive, so you don’t breathe a lung full of water in the event of unconsciousness.
Nope! That applies to snorkelers as well!
Of course, if you’re old school like me, and you came up the other way, as soon as you start freediving you’ve got a habit that you’ve got to change. The habit you learned first is the one that sticks. In instructional psychology we are still trying to figure out why this is. Of course, new divers are getting the right habits from the beginning, so they’re not going to have to relearn them.
Yeah, I had that problem too. My freediving instructor had to keep reminding me to spit out my snorkel when I dived! You mentioned open water mermaiding. I’m familiar with mermaid performances but do they also go out and conduct mermaid dives? Would a mermaid say, “Hey, let’s put on our tails and go dive the kelp forest?”
Because there is so much crossover between the communities, you have people who enjoy mermaid diving, and this is what we covered in the advanced mermaid course. They go out and they mermaid in the open water. There can be many motivations.
There are certainly venues, you know the classic going back decades is Weeki Wachee, of course, where you can watch. And that is more serious mermaiding. Just put brackets around it. It’s a little different from what a recreational mermaid learns. But it’s still the idea.
Mermaids like to be in a natural environment and watch each other. If you are somewhere warm and nice—like Grand Cayman or Bonaire—and you are surrounded by beauty, it’s fun to go mermaiding. And if you’ve got underwater photographers who might want to take pictures of you, all the better.
Are you aware of the Korean drama, “Legend of the Blue Sea?” It’s set in Korea but it begins somewhere in the mid-Pacific. The actress who plays the mermaid is swimming around coral and gorgeous stuff. The story is about how she swims all the way to Korea. So that was the performance. In recreational mermaiding, they have fun doing this. It’s something that can be done together in nature. In that case, they typically wear masks so they can see clearly, and they’ll swim down and see the fish. So, it’s a neat little aspect of mermaiding.
That’s right, you need a dive mask, not swim goggles, because you wouldn’t be able to equalize.
Right, and that’s another area where mermaiding differs from other forms of diving. The mask is optional. Some people prefer them, and or wear contact lenses that need to be kept dry. Conversely, in a place that’s not going to bother the eyes, where you see well enough to navigate, some will forgo the mask altogether. In the China video, you saw both.
Let’s talk a little about what has been in place prior to PADI’s and other training agencies’ entrance into mermaiding. How did people learn to be mermaids? I do know there are several schools out there like the LA Mermaid School, and I think Weeki Wachee has a program as well. That’s likely some of it.
Well, it’s kind of all over the map, like what you see in most swimming programs or water programs. There are numerous mermaid schools, as you call them, and there would be a ranking of typically a beginner and then an intermediate level and so on. I would say that—and I want to be sure I’m talking generally here because there are exceptions all over, things are starting to solidify, and community standards are evolving. However, generally compared to what diving offers many mermaid programs were comparatively unsophisticated but safe as far as I could tell. I saw nothing that looked unsafe. Some of them were pool-only and you always have grown-ups there, because there are children in the program, things like that. On the other hand there are some very sophisticated professional mermaid schools like LA Mermaid School and the Weeki Wachee program that offer top notch professional training.
I think what diving has brought to mermaiding is our experience in water safety and integrating it with breath-hold diving. If you take a PADI program, for example, and you are going to be a mermaid diver, you don’t need to be anything else. You just need to be okay on the medical (as any diver of any type), have basic swimming ability, and we’ll take it from there. You don’t have to be a “diver.” You’ll learn what you need to know to be a mermaid, which includes the stuff that’s come over from the other forms of diving.
I looked at the requirements. You need to be able to swim of course.
Yeah. And if you get right down to it, almost all water sports have that. If you fall in the water, it would be good if you knew how to swim. Seems like a good basic safety concept.
Ha! I also thought it interesting that your mermaid programs were open to pre-teens.
Yeah, it’s breath-hold diving, we don’t have the concerns we have with scuba. There’s not a risk of lung overexpansion injuries. We’re not concerned with the kind of depths that limit the junior divers to about 21 m/70 ft. On top of that, this is where we are able to borrow from the community that was there before we got involved. Traditional mermaid courses brought in kids. Kids do this great. They love it. They’ve already been doing it. So it’s not like we had to craft something new to make it fun for kids. Kids already know it’s fun.
We talk a lot in our industry about getting more young people into diving, given the increasing average age of the scuba diving community. Looks to me like mermaiding has the potential to get more young people underwater which is what we want, right?
Absolutely, but also what you’re describing is Western-centric, and changing. We are seeing more young people getting certified. But when you go to the Eastern Hemisphere, it’s like our generation was when we were in our 20s and 30s. That’s who is going diving, the young people. And it’s huge, and I would say it’s much more social there as well.
The ADEX shows are filled with young people. It’s a very different demographic than the US or Europe.
There is a senior crowd there as well. Interestingly, for a long time PADI Japan was top age heavy because of the demographic of their country, but now that is changing as more young people get involved.
Traditionally, Asian cultures have been better at revering the older generation than Western cultures, because they recognize that’s where wisdom lies. So, you bring the innovation and the enthusiasm of youth, and you pair it with the wisdom and lessons of the past. That’s where you get a really strong community. You can probably tell: I really admire that they bring that to our diving community.
PADI has a bazillion dive centres around the world. Are we going to start seeing mermaid programs and communities popping up everywhere?
I would say yes. It’s happening as we speak. I mean it has never happened before: a program was a fringe program, a specialty, that was going to be it. The market was that small. But like I said, the pandemic changed that like it changed so many things. We’ve never seen a program that went from essentially a fringe activity to something worthy of our full support with e-learning in a year and a half! I’ll tell you what, I’ve never had to type so fast in my life.
To me it’s exciting. It’s like, wow. Because diving could either have fallen on its face during what happened or it could do something new. And we’ve done something new. I mean it wasn’t “new new,” but it was new in the expansion and the attention it got and that caused it to grow. The community is even plugging into dedicated deep pools like K-26 in Korea, one of those purpose-built deep pools that goes down to 26 m/85 ft.
Ah yes, deep pools. We have a story about deep pools in this issue.
There are a number in Europe, and there are some being planned for the US. Mermaiding blends beautifully with these. Because it’s more than a pool but not quite open water, but you’ve got the controlled conditions, and you have depth. The freediving community has taken advantage of these, too. Most of these facilities have underwater windows as well. So now, in addition to performance art, you have the potential to make it a spectator sport, if you will, in diving.
Yeah, that’s really interesting. Talk to me about training. We will, of course, include links with the article about your courses etc., but tell me, what do you need to learn to be a mermaid? What is the main focus of the courses?
As I mentioned, a lot of it is stuff you’d learn as a freediver, but applied to mermaids. The first thing you learn is about the costumes because that’s a little different. What is or is not an appropriate mermaid tail? Because you can buy some out there that are purely costumes, they are not for swimming. You learn to swim in them, so there is a huge emphasis on dolphin kick. You learn breathing techniques. But again, as a mermaid, you may not have a snorkel or whatever so you learn how to float, you learn how to wade as a mermaid. At the same time, you are also learning to be a safety buddy. What do I have to watch? I’ve got to have these fins on, things like that.
Is mermaiding a team activity built around two or three people mermaiding together?
Like other forms of diving, you can’t paint too tight a box around that. But what we teach is that you have somebody watching you. It wouldn’t be considered reasonable to have two mermaids on the bottom and one safety diver. But if you were diving in threes, say, one person would go down and then come back up and then another goes down and comes up, and then the third, so it’s a bit like free diving. In open water, the safety diver might escort you through the last 5 m/15 ft. But in pool-based mermaiding, just like in pool-based free diving, the safety diver just stays on the surface.
They learn skills that were developed in freediving but have been mermaid adapted. Like doing a duck dive, which is a little bit different in a tail than in bi-fins. You learn some skills unique to mermaiding. There are more flourishes. Like C-shaped turns and back turns and the mermaid kiss. All these things that they love to do. Team handshakes. They get into the performance a little bit.
The instructor also has the latitude to help the mermaids try the makeup. And again, it’s not your typical Mary Kay. It has to be two things. It has to be waterproof and then if you’re in open water, it has to be environmentally friendly. It can’t be something that would hurt the environment. In our program, the mermaids are taught about the environment and our role as stewards, and they are encouraged to join the community of torchbearers who are trying to speak for the oceans.
You incorporate ocean and water conservation!
Yeah. All our programs have that tie. If you love the ocean, you can see what’s happening. You can also see that we can do something about it. And the most important thing right now is we all have a voice and a purpose when we come together on that.
I’ll run slightly into the weeds here, but you may have heard a few years ago that Drew [PADI CEO Drew Richardson] committed the PADI family to one billion torchbearers by 2050. And that’s actually not that huge a number. Drew also didn’t just pull that number out of the air. When you look at social tipping points, the amount of the population that has to adopt a new view before society tips in that direction, one billion is about half that number.
That’s a laudable goal!
So, obviously, when we start talking to mermaids, a lot of those folks are a crowd from outside our normal sphere. Of course, we want them to understand about the oceans and have a connection to it.
They are ambassadors. They are performing for people who may not be water people.
The potential for a mermaid to get in front of non-divers is in some ways better and at least different. And so they are reaching a new audience. Look at Mermaid Linden . How many kids does she talk to? You start talking with her about the ocean, and you won’t leave without knowing that it’s in trouble, it’s worth saving, and we can do it. She’s reminding six-year olds that they can help.
That’s powerful. I don’t know that the scuba community even talks to six-year olds. Get them while they are young, right? Karl, you and your colleagues have been involved in the development of many, many training programs. Was there anything unique or challenging about creating a mermaid program?
I’d say, fortunately, we’ve done this enough that we have learned where to look. In the past, I would’ve said that the challenge might have been finding the experts that we needed to go over what you’ve done and help us look for gaps and things like that. I would say, if there was any challenge, it would be this, and that was when we got to the e-learning part.
Because of the lockdowns and everything we were very limited in what we could do in terms of finding talent and locations and photographers. We always try our best to show as much multicultural diversity as possible in our products, but this one had to be shot entirely by our China team. We were able to get some stock photos and so on to show more than Asian faces, but you can tell, if you look at the program, that they handled the imaging for us.
But I’ll have to say, if we had to have a challenge, I’ll take that one any day of the week. They did a great job with what they did. They found some really, really talented mermaids to act in the stills and videos. We found enough stock shots of other faces that we could show our diversity. Plus, anybody who knows us, knows that we are probably the most culturally diverse group in diving.
PADI is not the only agency to see an opportunity. SSI launched their mermaid program in 2018. NAUI launched theirs in 2020. As far as Global Underwater Explorers (GUE) is concerned, I don’t expect to see “MER 1” anytime soon. But who knows? Do you anticipate more agencies jumping in on the tail wagon, as it were?
Yes, I believe we are going to see others pick this up as well as it grows. Success breeds competition. It’s happening, but that’s cool.
I remember once asking undersea pioneer Phil Nuytten, who invented the modern one-atmosphere suit, if he expected to have any competitors. He told me, “I hope we have competition. In fact, I hope we have a lot of competitors. Because if we don’t, it means that it wasn’t a very good idea.” I’m guessing that the people at SSI and NAUI are at least feeling validated!
Competition also keeps everyone sharp!
All the better for the mermaids, right? You launched your program in December 2020, and then last April PADI held this huge extravaganza in China. It was what, the largest underwater mermaid show ever?
The event was held at Atlantis Sanya in China and it set a Guinness World Record in their giant aquarium. It involved more than 100 PADI Mermaid divers, plus support divers and topside personnel. The divers spent three days rehearsing a synchronized dive—you can imagine what it takes to get 100+ divers to descend at the same time and then swim in a coordinated manner. It was spectacular though—and had a lot of international coverage.
I heard that the event got 170 million views on TikTok—OMG!—and PADI now has something like 600 mermaid instructors and 50 dive centers in China offering your mermaid program.
I don’t know the numbers off the top of my head, but yes, the PADI Mermaid Program has gotten a lot of attention around the world. More than 600 instructors in China alone sounds right – it’s been eye-opening.
Talk to me a little about technology. Do your courses deal with working with surface supplied gas, or scuba, or the use of nitrox as a pre-breathe? Would that be technical mermaiding? Ha!
It’s not within our program nor any of the programs you’ve mentioned, to my knowledge. It wouldn’t surprise me if we get there. Now I do know that the Weeki Wachee program, which has been around for years, is training professionals. There you have to be a scuba diver because you are going to breathe compressed air, if I am not mistaken. Of course, you have to know how important it is to be exhaling as you ascend. Exactly the opposite of what you would normally do as a free diver or mermaid diver. Right now, that kind of thing is outside of what recreational mermaiding, for lack of a better term, is about. But come ask me again in a few years. I’m serious. We saw freediving do it, right? You just said it—technical free diving. Whoever thought, oh, I can breathe up using a gas with a high oxygen fraction and stay down longer on my one breath. That’s helpful. Who knows? One of the cool things about diving is that divers tend to get what they want instead of what someone thinks they ought to want.
I was speaking to Virginia Hankins at the LA Mermaid School and SHEROES Entertainment that provide professional mermaids for film and photoshoots and professional engagements. They are trained to use underwater breathing equipment. She’s one of your instructor trainers.
Yes, absolutely. We were talking about “Legend of the Blue Sea” earlier, and I’m sure it was true in “Splash”—when you start talking about Hollywood productions, they are going to use scuba. Again, that’s beyond what we are teaching in our recreational program. It requires additional education.
Let’s talk about equipment. I attended Eric Albinsson’s webinar on PADI mermaiding. He said that the global mermaid tail market was valued at $80 million in 2020—that’s annual revenue, and was expected to grow to $150 million by 2026, a compound average growth rate (CAGR) of 9.5%. That blew me away!
I don’t know what number he’s quoting, but it’s definitely there. And again, it’s not new, if you think about it. In our courses, the minimum is a monofin. But look at the variety of tales in that China mermaid video.
They’re exotic and amazing. Some of them look like a real biological tail!
Yeah, so there’s absolutely a market that’s growing. And it’s been there, but it’s accelerating. And again, the pandemic probably helped it.
Obviously, PADI sees this as a business opportunity, not just for itself, but for its dive centers, instructors, and professionals.
Absolutely. For one thing, it’s reaching a new market, and some of these people will likely get exposed to freediving and scuba. So, you get this neat cross-pollination of the three markets, or rather the three communities. The second thing is, it’s a great resource to use. If you have a pool, or if you go to a pool a lot, you can do a lot there. People can go all the way through mermaid without going to open water. So, the center can offer two full certifications, plus the experience. If I ran a dive center, I would definitely at least be dabbling in it right now. I don’t think I’d want to ignore it.
It seems to me it’s a lot like adding freediving to a scuba center.
It’s similar. Your upfront investment isn’t that high. If you’ve got an instructor who wants to get into it, that person trains up and they learn to teach. You don’t need to buy another compressor or a mixed gas blending system. If you’re already catering to freedivers, you’ve already got all that covered. So basically, you’re talking about adding mermaid tails.
Tails! There we go again. I’ve often thought our job as an industry is just to get people into the water. Create water enthusiasts and then they’ll find whatever pathways work for them. Mermaiding is another fun thing to do in the water.
Last question: Where do you see this going? Where will mermaiding be ten or fifteen years from now?
Boy, that’s such a hard one to call because if you had asked me that question a year and a half ago, I would’ve said, “Well, maybe we’ll have a supplemental program someday.” And here we have a full e-Learning program we’re about to debut.
I don’t want to call this one. It’s going to grow. I can say that with confidence because it’s got the inertia now, it’s already happening, it’s already popular, and it’s global. There’s attention to it. It’s beautiful, it gets people in the water. There isn’t a whole lot to say against it. So, it’s going to be bigger. How much bigger? I don’t know. It could really take off in some communities that have not been connected to diving, where that visual appeal is important, and there are a lot of young people involved.
Thanks Karl. Call me crazy, but I find all of this really interesting.
The Darker Side of Mermaids
The Filthy Mermaid: Got-To-Have-Goods for For Mermaids Gone Bad
MerFest International 2021 (South Haven, MI 20-22 August, 2021)
Mermaids In Paradise (Ramrod Key, Fl 15-22 September, 2021)
PADI: How To Become a Mermaid
Michael Menduno/M2 is InDepth’s editor-in-chief and an award-winning journalist and technologist who has written about diving and diving technology for more than 30 years. He coined the term “technical diving.” His magazine “aquaCORPS: The Journal for Technical Diving” (1990-1996), helped usher tech diving into mainstream sports diving and he produced the first tek.Conferences and Rebreather Forums 1.0 & 2.0. In addition to InDepth, Menduno serves as an editor/reporter for DAN Europe’s Alert Diver magazine, a contributing editor for X-Ray mag, and writes for DeeperBlue.com. He is on the board of the Historical Diving Society (USA), and a member of the Rebreather Training Council.
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