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The Case for Biochemical Decompression
How much do you fart during decompression? How about your teammates? It turns out that those may be critical questions if you’re decompressing from a hydrogen dive, or more specifically hydreliox, a mixture of oxygen, helium, and hydrogen suitable for ultra-deep dives (Wet Mules, are you listening?). Here the former chief physiologist for the US Navy’s experimental hydrogen diving program, Susan Kayar, gives us the low down on biochemical decompression and what it may someday mean for tech diving.
by Susan R. Kayar, PhD
Header courtesy of A. Tocco Comex
Thirty years ago, the Naval Medical Research Institute (NMRI) in Bethesda, Maryland, hired me for what at the time I thought was the coolest job I could ever be asked to do. I still think so. I was hired to be the physiologist for their experimental hydrogen diving program. Why dive with hydrogen? A recent InDepth article by Reilly Fogarty, “Playing with Fire: Hydrogen as a Diving Gas”, does an excellent job of explaining this subject. The short answer: because hydrogen is the smallest molecule.
One might think that in an era with excellent one-atmosphere hard suits, and multiple forms of submersibles and robotics, there is no need to send bare-naked divers to the sorts of depths involved in hydrogen diving, as will be described shortly. If these alternatives to divers are so great, why do we still use commercial divers at all? One needs to ask an operational person this question, rather than a scientist like me. But I think the words “logistics”, “costs”, “safety,” and “the direct human touch” would figure in the answers.
Once a diver dives deep enough to exceed safe limits with regard to nitrogen narcosis, the usual gas switch for the diluent to oxygen is helium. However, if a diver keeps on going into the range of 1000 to 2000 feet of seawater (roughly 300-600 msw), a helium-oxygen gas mixture becomes dense enough that the work of breathing becomes difficult. Divers fight to move this dense gas into and out of their lungs, making the effort to breathe a serious source of fatigue and a distraction to their assigned jobs. (See “Maintaining Your Respiratory Reserve,” by John Clarke). Hydrogen is a diatomic molecule (i.e. H2) with two protons and no neutrons, and is therefore half the molecular weight of helium, a monatomic molecule with two protons and two neutrons. Therefore replacing helium with hydrogen, eases a diver’s respiratory distress i.e. work of breathing.
There is also a phenomenon of ultra-deep diving known as High Pressure Neurologic Syndrome, or HPNS, (also known as High Pressure Nervous Syndrome) which is evidently a function of high pressure interfering with the transmission of signals in the nervous system. Symptoms of HPNS can range from tremors to confusion to psychosis and are highly variable in depth at onset and from diver to diver. For unknown reasons, hydrogen at high pressure is narcotic and can suppress HPNS. Past a very high pressure that again varies with the diver, but generally on the order of 23 atmospheres partial pressure of hydrogen, its narcotic properties can become overwhelming and have their own psychotic effects.
There are also serious issues involving the explosivity of hydrogen in combination with oxygen, but these issues are manageable with the care one always uses in handling oxygen and other combustible and hyperbaric gases. Hydrogen and oxygen can be combined safely if the oxygen content is less than 4% of the gas mix, with dive operations usually opting for 2% oxygen as their safe upper limit. A 2% oxygen mixture is breathable if the total pressure is 10 atmospheres (roughly 90m/295 f) or more. This is normally accommodated by starting a pressurization with helium and then switching to hydrogen after 10 atm. As a final consideration, the price of helium is rising, and may make hydrogen substitution increasingly attractive. Consequently, for a variety of practical reasons, hydrogen has a potential place in ultra-deep diving beyond 10 atmospheres of pressure.
Investigating Biochemical Decompression
As the physiologist to the hydrogen diving program at NMRI, my assignments were two-fold: first, to determine if there are any dangerous biological effects that had been previously overlooked of breathing hyperbaric hydrogen, and second, to look into something that NMRI was calling “biochemical decompression,” or “biodec,” a term they had coined themselves.
The unknown dangerous biological effects portion of the research was addressed first. The short answer to that was “none”. We found no evidence that inhaled hydrogen could participate in any unwanted biochemical reactions in the body, discounting whatever reactions eventually make hydrogen narcotic. We still do not know exactly why hydrogen becomes narcotic, but it is unlikely from the physical properties of hydrogen that its narcotic effects are permanently harmful post-dive.
Then we got to the really exciting part of the hydrogen research program at NMRI: biochemical decompression. A few years before I was hired in 1990, a biochemist at NMRI, Dr. Lutz Kiesow, heard it was possible for divers to use hydrogen as a breathing gas. He knew there were many microbes that possessed a hydrogenase enzyme allowing them to consume hydrogen gas as a metabolic source equivalent to the consumption of oxygen as a metabolic source for most land organisms. End products for hydrogen metabolism can vary with the microbe, but is often methane (CH4). Hence, as a class, such microbes are called “methanogens”.
Dr. Kiesow proposed that NMRI establish a research project to isolate the hydrogenase from a methanogen, and insert it somewhere in the body of a diver to effectively create a chemical scrubber unit for hydrogen. If a diver could continuously scrub out some of the hydrogen going into solution in his body during the dive, the diver would have a reduced body burden of inert (to the diver) gas, and could subsequently decompress more rapidly with lower risk of decompression sickness (DCS).
What a cool concept! I loved it from the moment I heard it. But the real challenge was to resolve Dr. Kiesow’s “somewhere in the body” requirement into a safe, readily reachable, functionally useful body location. The director who hired me understandably warned me that divers would be opposed to receiving routine injections, or any sort of biological implant making them Bionic Men, permanently different from their former selves or from other divers. So what was left?
On my first musings with the scientific head of NMRI when I was hired, I wondered if we could perhaps encapsulate the hydrogenase enzyme, or better yet just whole methanogens, and swallow the capsules down for delivery to the large intestine as the working location for this scrubber unit. The scientific head instantly responded he had been thinking the same thing, but had not wanted to bias my thinking by saying it first. The approach met all our criteria. Taking capsules by mouth is as easy and as non-invasive a way to get things into the body as there can be. The large intestine has many microbial species living there safely and performing many jobs that we are slowly realizing are important to our health.
Trust Your Gut?
Methanogens typically are anaerobic organisms that would die quickly if exposed to oxygen, and the large intestine is the only part of the body that provides an anaerobic environment. Some species of methanogens are even a normal part of our intestinal flora, where they consume traces of hydrogen manufactured by other intestinal microbes. We were therefore confident that adding more methanogens should do no digestive harm. The amplified population of methanogens in the intestine would be likely to stay high only for as long as the divers breathed hydrogen, and return to baseline shortly after the exposure to hydrogen ended. The methane end product of this hydrogen scrubbing has a safe means of escaping from the intestine.
The methane-releasing issues were the only parts of this research that got a little weird at times. I was very carefully coached by Navy people to use lengthy euphemisms such as “the methane is released to the environment following the path of least resistance,” or “methane has an obvious means of egress from the intestine.” I was warned never to use what I have come to refer to as “the four-letter f-word” for methane release. But the euphemisms never helped. All audiences instantly understood the euphemisms as such.
Indeed, I came to consider it a sign that my audience was truly listening to me and following the science when they suddenly started squirming in their seats and trying with greater or lesser success to cover their laughter when I started explaining the fate of methane. Jokes followed. One Navy brass listener asked me if the implementation of hydrogen biochemical decompression meant a negation of the stealth intended for Navy SEALs when they used closed-system (i.e., non-bubbling) breathing rigs. The only sensible thing for me to do was laugh along with the room.
An interesting phenomenon happened as soon as people got over their initial laughter at this childishly scatological word that I did not say but that they obviously thought of themselves. They started thinking about the physiology and the gas transfer physics I was describing, and they liked it. No more laughter after that moment of enlightenment arrived. So go ahead and laugh now. “Better out than in” applies to laughter also. I got a million of ’em. I am known in some circles as the “Queen of Farts” with good reason.
Measuring Flatulence err Farts
I retired from Navy civilian service years ago, so I can say whatever I wish. I measured farts. Measuring farts is funny. And measuring farts in rats and pigs is exactly how my NMRI team and I succeeded in demonstrating the feasibility of hydrogen biochemical decompression to reduce the incidence of DCS following hydrogen dives by roughly half. As far as we know, methane release rate is the only variable that can be biologically manipulated with a measurable effect on DCS incidence following any kind of dive. There is nothing humorous about reducing DCS incidence.
The methanogenic species we chose has a rather grand first name but oddly mundane last name: Methanobrevibacter smithii. It is native to the intestinal flora of many mammals, including humans and pigs, and thus does not cause digestive issues when added to the intestines. The metabolic equation for M. smithii is the following:
4H2 + CO2 = CH4 + 2H2O
To speed things along in the lab, we surgically injected M. smithii cultures into the upper end of the large intestines of our lab animal models of divers, which were initially rats and later pigs. The animal-divers were then placed in a hyperbaric chamber which we pressurized with hydrogen and oxygen. Some hydrogen and oxygen breathed by an animal-diver dissolves in the blood for transport throughout the body. When the blood circulates through the vasculature of the intestinal wall, some hydrogen diffuses down its partial pressure gradient into the intestinal cavity, where the M. smithii are housed.
Oxygen is taken up by the cells of the intestinal wall and aerobically metabolized to carbon dioxide (CO2), some of which also diffuses into the intestinal cavity. M. smithii metabolizes the hydrogen and carbon dioxide to methane and water. The animal-diver safely absorbs the water. It is a real scientific benefit that the methane exits the body as easily as it does. Since no mammalian cell manufactures methane, we could track the metabolism of our methanogens inside our animal-divers simply by measuring the rate of release of methane from them to the surrounding environment by gas chromatography. As the hydrogen pressure in the chamber increased, we measured increasing quantities of methane in the chamber gases
When we then decompressed our animal-divers, on average, the animals with supplemental methanogens had approximately half the incidence of DCS as those without supplements. As the volume of methane they released during the dive increased, their incidence of DCS decreased.
Knowing from the metabolic equation above that four hydrogen molecules are consumed for each methane molecule manufactured, we could easily estimate the rate of hydrogen-scrubbing inside our animals. Based on the solubility of hydrogen in body tissues (which we guesstimated as being similar to water), and the time at pressure of the dive, we could estimate how much hydrogen would dissolve in an animal of a given body mass by the end of the bottom time, and what fraction of that body burden of hydrogen had been eliminated by our process. We computed that when M. smithii eliminated approximately 5% of the hydrogen dissolved in our animal-divers’ bodies, DCS incidence was reduced by 50% (Fahlman et al, 2001).
Human Biodec
Having succeeded in demonstrating hydrogen biochemical decompression in a small animal model, the rat, and a larger animal model, the pig, we are at least scientifically prepared to extend this work to human divers. A diver would make a saturation dive (commonly abbreviated to “sat”, meaning a dive sufficiently long i.e. 24 hours or more, to saturate the diver’s tissues with the breathing mixture) using a hydrogen-oxygen blend we usually call “hydrox”, or a hydrogen-helium-oxygen trimix which goes by the awkward name of “hydreliox”, depending on practicalities.
Dive operations may even opt for a quad-mix including nitrogen. The ultra-deep diving trials at Duke University found the narcotic properties of nitrogen helped to suppress HPNS, which was so problematic for their divers breathing heliox. However, the interaction is complex. Since we are still working out the exact mechanisms that make nitrogen and hydrogen narcotic under pressure, it remains to be determined if combining nitrogen and hydrogen for deep sat dives makes narcotic issues better or worse. The issue deserves testing.
Regardless of the other gases in the sat diver’s mix, if there is hydrogen, then hydrogen biochemical decompression could be considered. A couple of days before the end of the bottom time, the diver would prepare to biochemically decompress as a supplement to the physical decompression. The basic process would be identical to that for our animal models, except for a gentler way of delivering the methanogens to the diver. We would freeze-dry cultures of M. smithii and pack them into oral-delivery capsules designed to dissolve only under the conditions inside the large intestine. It would take around 24-36 hours to have a capsule arrive in the intestine, dissolve, and re-activate the methanogens. We would know that the M. smithii were on site and sufficiently active by chemically analyzing the sat chamber gases for methane output. Then we would get to watch the diver not bend as he decompressed faster than divers in other hydrogen diving operations without biochemical decompression. As I said, coolest job ever, or what?
But wait!
There is one more really exciting finding to report. We have evidence that even the quantity of methanogens native to the intestinal flora of a pig can provide sufficient hydrogen-scrubbing activity to reduce DCS incidence from a hydrogen dive (See Fig. 4 below). Humans and pigs are similar in many respects, including basic intestinal flora. It may well be that any human divers on a hydrogen dive, such as those at COMEX , have already benefited from hydrogen biochemical decompression without realizing it. They have only to test for methane in their chamber gases to know.
Skeptics have argued that the relatively small percentage of hydrogen scrubbing we have computed may be far too little to have any impact on DCS risk in human divers or to make a worthwhile reduction in decompression times. In addition to pointing to our DCS incidence data, we note that all divers are familiar with how important small differences in gas loads can be in DCS risk. If we dive within the time at depth limits of our chosen algorithms, we are confident to a very high level of probability that our dive will end safely. But exceeding our planned no-decompression limits by even a few minutes, and thus adding only a relatively small percentage increase in our inert gas load beyond what we think of as safe, makes our dive profile much riskier. [Ed. Note: These are computational risks not necessarily operational ones i.e. small changes in times/depths are unlikely to result in DCI] Likewise, we are all in the habit of making what we term a “safety stop” in 3-5m/10-15 ft even from a low-risk, no decompression time-requiring dive.
Sat dive operations currently using heliox and contemplating a shift to adding hydrogen will be dismayed to realize that hydrogen is considerably more potent at inducing DCS than is helium (Lillo R.S., E.C. Parker, W.C. Porter, 1997 Decompression comparison of helium and hydrogen in rats. J. Appl. Physiol. 82(3) 892-901). This would mean that costs saved by substituting relatively inexpensively manufactured hydrogen (by electrolysis of water) for increasingly expensive imported helium could be overwhelmed by the costs added in significantly longer decompression time. This is where hydrogen biodec may provide its greatest advantage: in shaving down the extra time needed for safe decompression from a hydrogen dive to something closer to that of a heliox dive. Until someone takes the step of testing hydrogen biodec in human subjects, we will not know to what extent operational decompression times could be reduced.
Nitrogen Biodec?
What comes next? In an ideal scientific world, our research in animal models would be followed by equivalent studies in human divers. However, for the time being in the post-Russian Cold War Era, the US Navy has expressed no further interest in hydrogen diving and has not offered to support human studies in hydrogen biochemical decompression. To assuage my disappointment, I wrote a novel in which hydrogen biochemical decompression is used to help save the day in a submarine rescue scenario. The novel is entitled “Operation SECOND STARFISH, A Tale of Submarine Rescue, Science, and Friendship,” available as a paperback and Kindle e-book on Amazon.
But I am still dreaming bigger than that. Since hydrogen biochemical decompression works, why not shoot for something everyone in the diving world could use? Nitrogen biochemical decompression! There are nitrogen-metabolizing microbes native to our intestinal flora. But the problems of experimentally making nitrogen biochemical decompression work are staggeringly complicated. One of many is that in nitrogen metabolism, usually referred to as nitrogen fixation, the end-products are molecules such as nitrites, nitrates, and ammonia, which are not gases that would just come bubbling out for us to measure.
These fixed nitrogen compounds would stay dissolved in the fecal material and join many more such molecules already there from protein digestion. (If you think the fart jokes are bad, consider the fecal jokes. “No shit!”-Ed.) The presence of fixed nitrogen products in feces (also known as “fertilizer” under other circumstances) suppresses the nitrogen-fixing microbes from fixing even more, since the process is energetically expensive to the microbes and done only by necessity. It would take some genetic manipulation of the microbes to get them to work for us, and some form of special molecular labeling to measure how much end products they are making. I leave those problems to future scientists to solve, while I enjoy my retirement in New Mexico, the Land of Enchantment, and go on dive vacations to Hawaii, Papua New Guinea, Tahiti, Fiji, and Raiatea to keep my vestigial gills damp. I may even write another novel.
Dive Deeper
Operation SECOND STARFISH, A Tale of Submarine Rescue, Science, and Friendship
References
Bennett, P.B., R. Coggin, M. McLeod, 1982. Effect of compression rate on use of trimix to ameliorate HPNS in man to 686 m (2250 ft). Undersea Biomed. Res. 9(4)335-51.
Fahlman, A., P. Tikuisis, J.F. Himm, P.K. Weathersby, and S.R. Kayar, 2001. On the likelihood of decompression sickness during H2 biochemical decompression in pigs. J. Appl. Physiol. 91:2720-2729.
Imbert, J.P., C. Gortan, X. Fructus, T. Ciesielski, and B. Gardette, 1988. Ch. 13. Hydra 8: Pre-commercial Hydrogen Diving Project. Advances in Underwater Technology, Ocean Science and Offshore Engineering, Vol. 14, pp 107-116.
Kayar, S.R., M.J. Axley, L.D. Homer, and A.L. Harabin, 1994. Hydrogen gas is not oxidized by mammalian tissues under hyperbaric conditions. Undersea Hyperbaric Med. 21(3):265-275.
Kayar, S.R. and M.J Axley, 1997. Accelerated gas removal from divers’ tissues utilizing gas metabolizing bacteria. U.S. Patent No. 5,630,410.
Lillo R.S., E.C. Parker, W.C. Porter, 1997 Decompression comparison of helium and hydrogen in rats. J. Appl. Physiol. 82(3) 892-901
Kayar, S.R., T.L. Miller, M.J. Wolin, E.O. Aukhert, M.J. Axley, and L.A. Kiesow, 1998. Decompression sickness risk in rats by microbial removal of dissolved gas. Am. J. Physiol. 275 (Regulatory Integrative Comp. Physiol. 44):R677-682.
Kayar, S.R., A. Fahlman, W.C. Lin, and W.B. Whitman, 2001. Increasing activity of H2-metabolizing microbes lowers decompression sickness risk in pigs during H2 dives. J. Appl. Physiol. 91:2713-2719.
Kayar, S.R. and A. Fahlman, 2001. Decompression sickness risk reduced by native intestinal flora in pigs after H2 dives. Undersea Hyper. Med. 28(2)89-97.
Valée, N., Weiss M., Rostain JC, Risso JJ, A review of recent neurochemical data on inert gas narcosis. Undersea Hyper. Med. 38(1)49-59
Susan grew up in the St. Louis, Missouri, area. An early fascination with the films of Jacques Cousteau inspired her to become certified as a scuba diver while still in high school. Her diving in Missouri was confined to artificial lakes with sunken rowboats, lost Coke bottles, and a few carp as the thrills. She persevered in her interests in marine sciences and attended the University of Miami as a biology major, remaining at that institution all the way through to a doctorate. After graduation, it did not take long to realize she would starve if she insisted on a job in marine biology, so she moved into studying physiology in extreme environments and exercise stress. Postdoctoral research appointments sent her from Colorado to Switzerland to New Jersey. Her dream job finally materialized in an appointment with the US Navy in the Washington, DC area, where she studied decompression sickness risk in animal models of ultra-deep diving.
Susan was inducted into The Women Divers Hall of Fame in 2001 in recognition of her Navy diving research. When funding for her Navy program ended, she managed research funding efforts for the National Institutes of Health (NIH), Defense Advanced Research Programs Agency (DARPA), and the Office of Naval Research (ONR). Now in retirement, she has written a diving-themed novel, “Operation SECOND STARFISH.”
Community
Twenty-five Years in the Pursuit of Excellence – The Evolution and Future of GUE
Founder and president Jarrod Jablonski describes his more than a quarter of a century long quest to promote excellence in technical diving.
by Jarrod Jablonski. Images courtesy of J. Jablonski and GUE unless noted.
The most difficult challenges we confront in our lives are the most formative and are instrumental in shaping the person we become. When I founded Global Underwater Explorers (GUE), the younger version of myself could not have foreseen all the challenges I would face, but equally true is that he would not have known the joy, the cherished relationships, the sense of purpose, the rich adventures, the humbling expressions of appreciation from those impacted, or the satisfaction of seeing the organization evolve and reshape our industry. Many kindred souls and extraordinary events have shaped these last 25 years, and an annotated chronology of GUE is included in this issue of InDEPTH. This timeline, however, will fail to capture the heart behind the creation of GUE, it will miss the passionate determination currently directing GUE, or the committed dedication ready to guide the next 25 years.
I don’t remember a time that I was not in, around, and under the water. Having learned to swim before I could walk, my mother helped infuse a deep connection to the aquatic world. I was scuba certified in South Florida with my father, and promptly took all our gear to North Florida where I became a dive instructor at the University of Florida. It was then that I began my infatuation with cave diving. I was in the perfect place for it, and my insatiable curiosity was multiplied while exploring new environments. I found myself with a strong desire to visit unique and hard-to-reach places, be they far inside a cave or deep within the ocean.
My enthusiasm for learning was pressed into service as an educator, and I became enamored with sharing these special environments. Along with this desire to share the beauty and uniqueness of underwater caves was a focused wish to assist people in acquiring the skills I could see they needed to support their personal diving goals. It could be said that these early experiences were the seeds that would germinate, grow, mature, and bloom into the organizing principles for GUE.
The Pre-GUE Years
Before jumping into the formational days of GUE, allow me to help you visualize the environment that was the incubator for the idea that became GUE’s reality. By the mid-1990s, I was deeply involved in a variety of exploration activities and had been striving to refine my own teaching capacity alongside this growing obsession for exploratory diving. While teaching my open water students, I was in the habit of practicing to refine my own trim and buoyancy, noticing that the students quickly progressed and were mostly able to copy my position in the water. Rather than jump immediately into the skills that were prescribed, I started to take more time to refine their comfort and general competency. This subtle shift made a world of difference in the training outcomes, creating impressive divers with only slightly more time and a shift in focus. In fact, the local dive boats would often stare in disbelief when told these divers were freshly certified, saying they looked better than most open water instructors!
By this point in my career, I could see the problems I was confronting were more systemic and less individualistic. In retrospect, it seemed obvious that key principles had been missing in both my recreational and technical education, not to mention the instructor training I received. The lack of basic skill refinement seemed to occur at all levels of training, from the beginner to the advanced diver. Core skills like buoyancy or in-water control were mainly left for divers to figure out on their own and almost nobody had a meaningful emphasis on efficient movement in the water. It was nearly unheard of to fail people in scuba diving, and even delaying certification for people with weak skills was very unusual. This remains all too common to this day, but I believe GUE has shifted the focus in important ways, encouraging people to think of certification more as a process and less as a right granted to them because they paid for training.
The weakness in skill refinement during dive training was further amplified by little-to-no training in how to handle problems when they developed while diving, as they always do. In those days, even technical/cave training had very little in the way of realistic training in problem resolution. The rare practice of failures was deeply disconnected from reality. For example, there was almost no realistic scenario training for things like a failed regulator or light. What little practice there was wasn’t integrated into the actual dive and seemed largely useless in preparing for real problems. I began testing some of my students with mock equipment failures, and I was shocked at how poorly even the best students performed. They were able to quickly develop the needed skills, but seeing how badly most handled their first attempts left me troubled about the response of most certified divers should they experience problems while diving, as they inevitably would.
Diving Fatalities
Meanwhile, I was surrounded by a continual progression of diving fatalities, and most appeared entirely preventable. The loss of dear friends and close associates had a deep impact on my view of dive training and especially on the procedures being emphasized at that time within the community. The industry, in those early days, was wholly focused on deep air and solo diving. However, alarmingly lacking were clear bottle marking or gas switching protocols. It seemed to me to be no coincidence that diver after diver lost their lives simply because they breathed the wrong bottle at depth. Many others died mysteriously during solo dives or while deep diving with air.
One of the more impactful fatalities was Bob McGuire, who was a drill sergeant, friend, and occasional dive buddy. He was normally very careful and focused. One day a small problem with one regulator caused him to switch regulators before getting in the water. He was using a system that used color-coded regulators to identify the gas breathed. When switching the broken regulator, he either did not remember or did not have an appropriately colored regulator. This small mistake cost him his life. I clearly remember turning that one around in my head quite a bit. Something that trivial should not result in the loss of a life.
Also disturbing was the double fatality of good friends, Chris and Chrissy Rouse, who lost their lives while diving a German U-boat in 70 m/230 ft of water off the coast of New Jersey. I remember, as if the conversation with Chris were yesterday, asking him not to use air and even offering to support the cost as a counter to his argument about the cost of helium. And the tragedies continued: The loss of one of my closest friends Sherwood Schille, the death of my friend Steve Berman who lived next to me and with whom I had dived hundreds of times, the shock of losing pioneering explorer Sheck Exley, the regular stream of tech divers, and the half dozen body recoveries I made over only a couple years, which not only saddened me greatly, but also made me angry. Clearly, a radically different approach was needed.
Learning to Explore
Meanwhile, my own exploration activities were expanding rapidly. Our teams were seeking every opportunity to grow their capability while reducing unnecessary risk. To that end, we ceased deep air diving and instituted a series of common protocols with standardized equipment configurations, both of which showed great promise in expanding safety, efficiency, and comfort. We got a lot of things wrong and experienced enough near misses to keep us sharp and in search of continual improvement.
But we looked carefully at every aspect of our diving, seeking ways to advance safety, efficiency, and all-around competency while focusing plenty of attention into the uncommon practice of large-scale, team diving, utilizing setup dives, safety divers, and inwater support. We developed diver propulsion vehicle (DPV) towing techniques, which is something that had not been done previously. We mostly ignored and then rewrote CNS oxygen toxicity calculations, developed novel strategies for calculating decompression time, and created and refined standard procedures for everything from bottle switching to equipment configurations. Many of these developments arose from simple necessity. There were no available decompression programs and no decompression tables available for the dives we were doing. Commonly used calculations designed to reduce the risk of oxygen toxicity were useless to our teams, because even our more casual dives were 10, 20, or even 30 times the allowable limit. The industry today takes most of this for granted, but in the early days of technical diving, we had very few tools, save a deep motivation to go where no one had gone before.
Many of these adventures included friends in the Woodville Karst Plain Project (WKPP), where I refined policies within the team and most directly with longtime dive buddy George Irvine. This “Doing it Right” (DIR) approach sought to create a more expansive system than Hogarthian diving, which itself had been born in the early years of the WKPP and was named after William Hogarth Main, a friend and frequent dive buddy of the time. By this point, I had been writing about and expanding upon Hogarthian diving for many years. More and more of the ideas we wanted to develop were not Bill Main’s priorities and lumping them into his namesake became impractical, especially given all the debate within the community over what was and was not Hogarthian.
A similar move from DIR occurred some years later when GUE stepped away from the circular debates that sought to explain DIR and embraced a GUE configuration with standard protocols, something entirely within our scope to define.
These accumulating events reached critical mass in 1998. I had experienced strong resistance to any form of standardization, even having been asked to join a special meeting of the board of directors (BOD) for a prominent cave diving agency. Their intention was to discourage me from using any form of standard configuration, claiming that students should be allowed to do whatever they “felt’ was best. It was disconcerting for me, as a young instructor, to be challenged by pioneers in the sport; nevertheless, I couldn’t agree with the edict that someone who was doing something for the first time should be tasked with determining how it should be done.
This sort of discussion was common, but the final straw occurred when I was approached by the head of a technical diving agency, an organization for which I had taught for many years. I was informed that he considered it a violation of standards not to teach air to a depth of at least 57 m/190 ft. This same individual told me that I had to stop using MOD bottle markings and fall in line with the other practices endorsed by his agency. Push had finally come to shove, and I set out to legitimize the training methods and dive protocols that had been incubating in my mind and refined with our teams over the previous decade. Years of trial and many errors while operating in dynamic and challenging environments were helping us to identify what practices were most successful in support of excellence, safety, and enjoyment.
Forming GUE
Forming GUE as a non-profit company was intended to neutralize the profit motivations that appeared to plague other agencies. We hoped to remove the incentive to train—and certify—the greatest number of divers as quickly as possible because it seemed at odds with ensuring comfortable and capable divers. The absence of a profit motive complemented the aspirational plans that longtime friend Todd Kincaid and I had dreamed of. We imagined a global organization that would facilitate the efforts of underwater explorers while supporting scientific research and conservation initiatives.
I hoped to create an agency that placed most of the revenue in the hands of fully engaged and enthusiastic instructors, allowing them the chance to earn a good living and become professionals who might stay within the industry over many years. Of course, that required forgoing the personal benefit of ownership and reduced the revenue available to the agency, braking its growth and complicating expansion plans. This not only slowed growth but provided huge challenges in developing a proper support network while creating the agency I envisioned. There were years of stressful days and nights because of the need to forgo compensation and the deep dependance upon generous volunteers who had to fit GUE into their busy lives. If it were not for these individuals and our loyal members, we would likely never have been successful. Volunteer support and GUE membership have been and remain critical to the growing success of our agency. If you are now or have ever been a volunteer or GUE member, your contribution is a significant part of our success, and we thank you.
The challenges of the early years gave way to steady progress—always slower than desired, with ups and downs, but progress, nonetheless. Some challenges were not obvious at the outset. For example, many regions around the world were very poorly developed in technical diving. Agencies intent on growth seemed to ignore that problem, choosing whoever was available, and regardless of their experience in the discipline, they would soon be teaching.
This decision to promote people with limited experience became especially problematic when it came to Instructor Trainers. People with almost no experience in something like trimix diving were qualifying trimix instructors. Watching this play out in agency after agency, and on continent after continent, was a troubling affair. Conversely, it took many years for GUE to develop and train people of appropriate experience, especially when looking to critical roles, including high-level tech and instructor trainers. At the same time, GUE’s efforts shaped the industry in no small fashion as agencies began to model their programs after GUE’s training protocols. Initially, having insisted that nobody would take something like Fundamentals, every agency followed suit in developing their own version of these programs, usually taught by divers that had followed GUE training.
This evolving trend wasn’t without complexity but was largely a positive outcome. Agencies soon focused on fundamental skills, incorporated some form of problem-resolution training, adhered to GUE bottle and gas switching protocols, reduced insistence on deep air, and started talking more about developing skilled divers, among other changes. This evolution was significant when compared to the days of arguing about why a person could not learn to use trimix until they were good while diving deep on air.
To be sure, a good share of these changes was more about maintaining business relevance than making substantive improvements. The changes themselves were often more style than substance, lacking objective performance standards and the appropriate retraining of instructors. Despite these weaknesses, they remain positive developments. Talking about something is an important first step and, in all cases, it makes room for strong instructors in any given agency to practice what is being preached. In fact, these evolving trends have allowed GUE to now push further in the effort to create skilled and experienced divers, enhancing our ability to run progressively more elaborate projects with increasingly more sophisticated outcomes.
The Future of GUE
The coming decades of GUE’s future appear very bright. Slow but steady growth has now placed the organization in a position to make wise investments, ensuring a vibrant and integrated approach. Meanwhile, evolving technology and a broad global base place GUE in a unique and formidable position. Key structural and personnel adjustments complement a growing range of virtual tools, enabling our diverse communities and representatives to collaborate and advance projects in a way that, prior to now, was not possible. Strong local communities can be easily connected with coordinated global missions; these activities include ever-more- sophisticated underwater initiatives as well as structural changes within the GUE ecosystem. One such forward-thinking project leverages AI-enabled, adaptive learning platforms to enhance both the quality and efficiency of GUE education. Most agencies, including GUE, have been using some form of online training for years, but GUE is taking big steps to reinvent the quality and efficiency of this form of training. This is not to replace, but rather to extend and augment inwater and in-person learning outcomes. Related tools further improve the fluidity, allowing GUE to seamlessly connect previously distant communities, enabling technology, training, and passion to notably expand our ability to realize our broad, global mission.
Meanwhile, GUE and its range of global communities are utilizing evolving technologies to significantly expand the quality and scope of their project initiatives. Comparing the impressive capability of current GUE communities with those of our early years shows a radical and important shift, allowing results equal or even well beyond those possible when compared even with well-funded commercial projects. Coupled with GUE training and procedural support, these ongoing augmentations place our communities at the forefront of underwater research and conservation. This situation will only expand and be further enriched with the use of evolving technology and closely linked communities. Recent and planned expansions to our training programs present a host of important tools that will continue being refined in the years to come. Efforts to expand and improve upon the support provided to GUE projects with technology, people, and resources are now coming online and will undoubtedly be an important part of our evolving future.
The coming decades will undoubtedly present challenges. But I have no doubt that together we will not only overcome those obstacles but we will continue to thrive. I believe that GUE’s trajectory remains overwhelmingly positive, for we are an organization that is continually evolving—driven by a spirit of adventure, encouraged by your heartwarming stories, and inspired by the satisfaction of overcoming complex problems. Twenty-five years ago, when I took the path less traveled, the vision I had for GUE was admittedly ambitious. The reality, however, has exceeded anything I could have imagined. I know that GUE will never reach a point when it is complete but that it will be an exciting lifelong journey, one that, for me, will define a life well lived. I look forward our mutual ongoing “Quest for Excellence.”
See Listings Below For Additional Resources On GUE And GUE Diving!
Jarrod is an avid explorer, researcher, author, and instructor who teaches and dives in oceans and caves around the world. Trained as a geologist, Jarrod is the founder and president of GUE and CEO of Halcyon and Extreme Exposure while remaining active in conservation, exploration, and filming projects worldwide. His explorations regularly place him in the most remote locations in the world, including numerous world record cave dives with total immersions near 30 hours. Jarrod is also an author with dozens of publications, including three books.
A Few GUE Fundamentals
Similar to military, commercial and public safety divers, Global Underwater Explorers (GUE) is a standards-based diving community, with specific protocols, standard operating procedures (SOPs) and tools. Here are selected InDEPTH stories on some of the key aspects of GUE diving, including a four-part series on the history and development of GUE decompression procedures by founder and president Jarod Jablonski.
Anatomy of a Fundamentals Class
GUE Instructor Examiner Guy Shockey explains the thought and details that goes into GUE’s most popular course, Fundamentals, aka “Fundies,” which has been taken by numerous industry luminaries. Why all the fanfare? Shockey characterizes the magic as “simple things done precisely!
Back to Fundamentals: An Introduction to GUE’s Most Popular Diving Course
Instructor evaluator Rich Walker attempts to answer the question, “why is Fundamentals GUE’s most popular diving course?” Along the way, he clarifies some of the myths and misconceptions about GUE training. Hint: there is no Kool-Aid.
As you’d expect, Global Underwater Explorers (GUE) has a standardized approach to prepare your equipment for the dive, and its own pre-dive checklist: the GUE EDGE. Here explorer and filmmaker Dimitris Fifis preps you to take the plunge, GUE-style.
The Flexibility of Standard Operating Procedures
Instructor trainer Guy Shockey discusses the purpose, value, and yes, flexibility of standard operating procedures, or SOPs, in diving. Sound like an oxymoron? Shockey explains how SOPs can help offload some of our internal processing and situational awareness, so we can focus on the important part of the dive—having FUN!
Standard Gases: The Simplicity of Everyone Singing the Same Song
Like the military and commercial diving communities before them, Global Underwater Explorers (GUE) uses standardized breathing mixtures for various depth ranges and for decompression. Here British wrecker and instructor evaluator Rich Walker gets lyrical and presents the reasoning behind standard mixes and their advantages, compared with a “best mix” approach. Don’t worry, you won’t need your hymnal, though Walker may have you singing some blues.
Rules of Thumb: The Mysteries of Ratio Deco Revealed
Is it a secret algorithm developed by the WKPP to get you out of the water faster sans DCI, or an unsubstantiated decompression speculation promoted by Kool-Aid swilling quacks and charlatans? British tech instructor/instructor evaluator Rich Walker divulges the arcane mysteries behind GUE’s ratio decompression protocols in this first of a two part series.
The Thought Process Behind GUE’s CCR Configuration
Global Underwater Explorers is known for taking its own holistic approach to gear configuration. Here GUE board member and Instructor Trainer Richard Lundgren explains the reasoning behind its unique closed-circuit rebreather configuration. It’s all about the gas!
GUE and the Future of Open Circuit Tech Diving
Though they were late to the party, Global Underwater Explorers (GUE) is leaning forward on rebreathers, and members are following suit. So what’s to become of their open circuit-based TECH 2 course? InDepth’s Ashley Stewart has the deets.
Diving projects, or expeditions—think Bill Stone’s Wakulla Springs 1987 project, or the original explorations of the Woodville Karst Plain’s Project (WKPP)—helped give birth to technical diving, and today continue as an important focal point and organizing principle for communities like Global Underwater Explorers (GUE). The organization this year unveiled a new Project Diver program, intended to elevate “community-led project dives to an entirely new level of sophistication.” Here, authors Guy Shockey and Francesco Cameli discuss the power of projects and take us behind the scenes of the new program
Decompression, Deep Stops and the Pursuit of Precision in a Complex World In this first of a four-part series, Global Underwater Explorers’ (GUE) founder and president Jarrod Jablonski explores the historical development of GUE decompression protocols, with a focus on technical diving and the evolving trends in decompression research.
Tren Maya is on the Wrong Track! An Update.
Doping for Depth
Hyperbaric Chambers Are Turning Away Divers. Will There Be One Nearby When You Need It?
Let There Be Mix!
Who You Gonna Call (in an Emergency)?
Über-deep with Cave Explorer Xavier Meniscus
Madagascar Madness
Sixty-year old Scubapro Dives into Tech (again)
