Connect with us

Cave

Data for Divers: Mexican Explorers Go Digital to Chart Riviera Maya

Mexico’s Yucatan Peninsula has long been the focus of underground exploration. Now a host of new tools such as digital surveying tools, mapping software, photogrammetry, drones, and augmented reality systems are making it easier for explorers to both collect data and share their findings with the world. InDepth sat down with veteran Yucatan explorer and geospatial scientist Sam Meacham to discuss his foundation’s extraordinary exploration efforts and get the lay of the land.

Published

on

By Michael Menduno

Photo by Sam Meacham CINDAQ AC

When I asked Sam Meacham how old he was during the course of our interview, he immediately quipped, “old enough to know better than to have dedicated my life to cave diving.” Fortunately, or unfortunately for Meacham, it would appear that his predilection won out. 

The ardent 53-year old explorer, diving instructor, conservationist, geospatial scientist, mapmaker and founder of El Centro Investigador del Sistema Acuífero de Quintana Roo, aka CINDAQ—whose mission is to facilitate research, promote education, and support conservation of the cenotes and underground rivers of Quintana Roo, Mexico,has spent more than a quarter of a century peering off into the darkness and returning to tell the tale. In CINDAQ’s case, this typically takes the form of map data, logs, pictures, photogrammetry, geospatial data, video, film, and documentaries (BBC, CNN, National Geographic and PBS), lending support to famed explorer Bill Stone’s observation that “the difference between exploration and adventure is data!”

Sam Meacham (front) before a dive.

In that regard, Meacham and his pioneering colleagues, Fred Devos and Chris Le Maillot, owners of Zero Gravity dive center, and others, have been extraordinarily prolific, shedding light on many hundreds of kilometers/miles of underground passageway that form the circulatory system of Riviera Maya, to the benefit of policy makers, scientists, and citizens alike. “We are building on the pioneering efforts of those who came before us and trying to build up the generation that will follow,” Meacham explained. 

In fact, over the last three years as a result of increased funding, new tools, and an enthusiastic pool of trained volunteers, they have actually stepped up their exploration and documentation efforts. Meacham, who was born in the U.S. and is also a naturalized citizen of Mexico and France, says they are just scratching the surface.

The New Frontier

One might say that the Yucatan, once considered the “new frontier” of cave diving back in the 1990s, occupies a special place in Sam Meacham’s diving firmament. In 1984, Meacham, then a lanky teenager, made his first dive during a PADI “Discover Scuba Diving” course while on family vacation in Akumal where he first met cave diving pioneer Mike Madden. He got PADI Open Water certification in Anguilla a year later. He was hooked.

Meacham returned to Puerto Aventuras nearly a decade later in 1994 to become a recreational diving instructor under Madden’s tutelage. That same year he completed his full cave certification with then National Association of Cave Diving (NACD) president Steve Gerrard. Meacham began work as an instructor at Madden’s CEDAM Dive Center, and later worked for Aquatech Villa DeRosa, where he learned from two additional cave diving mentors Gary and Kay Walten. It is also where Meacham first met Bil Phillips with whom he would share many adventures.

An RB-80 heads into Cenote Gea to explore. Photo Courtesy of CINDAQ.

The 1990s was a period of intense cave exploration in the Yucatan, as competing teams of divers sought to connect two gargantuan cave systems, Nohoch Nah Chich and Dos Ojos, and by doing so claim naming rights for the combined system. Meacham was in the thick of it.

Deciding to branch out on their own, Meacham, Phillips, Fred Devos, Bernd Birnbach, Chris Le Maillot, Daniel Riordan and Sabine Schnittger began the early exploration of the Ox Bel Ha system, which CINDAQ has carried on to this day. “I am extremely proud of what we accomplished,” Meacham said. “We were too young to know it was almost impossible.” Most of the expedition work at that time was self-funded. The group ended up buying a horse (to ferry gear into the jungle) and a compressor.

Forming CINDAQ

In 2000, Meacham founded CINDAQ, a nonprofit foundation and recognized non-government organization (NGO), to provide a legitimate mechanism to solicit and accept funding to cover the cost of exploration projects. Their first sponsor was Aguakan, the company that supplied water to Cancun, and which wanted the team to explore and map the area around the company’s wells and help create a campaign to raise awareness of water issues. 

Over the next eight years, CINDAQ was able to secure funding from numerous sponsors to continue their far-flung exploration of Ox Bel Ha, and later Sian Ka’an, including renting a helicopter to ferry divers gear to a jungle-locked cenote. He also participated in a number of documentaries including “Secrets of the Maya Underworld” and “Planet Earth: Caves” for various BBC units, “The Spirit of Nature,” for CNN, and forNational Geographic/PBS, “Strange Days on Planet Earth.” Many of these were filmed with Mike Madden with whom Meacham shares a passion of storytelling through film.

In 2009, Meacham was given the opportunity to go to graduate school and was accepted into a master’s degree program at the University of New Hampshire to earn a M.S. in Natural Resources with a specialization in geospatial science. His thesis: “Using Landsat 5 TM Data to identify and Map Areas of Mangroves in Tulum, Quintana Roo, Mexico,” used satellite data to locate and map mangrove in the Municipality of Tulum and down into the Sian Ka’an Biosphere Reserve. During this period, he put CINDAQ on hold. Upon graduation in 2012, he was offered a job as a research scientist and diving safety officer, at the Meadows Center for Water and the Environment at Texas State University.

CINDAQ Redux

In 2016, Meacham and his family moved back to their house in Mexico, and he began a reinvigorated effort to bring CINDAQ back to life. Meacham, who was now a Global Underwater Explorer (GUE) instructor and a member of the GUE board of directors, along with Devos and Le Maillot,were able to solicit private donations and, in cooperation with the volunteers at the Mexican Cave Exploration Project (MCEP), stepped up their exploration and mapping efforts. They focused on Ox Bel Ha and connecting caves further south into Sian Ka’an, which lies deep in the Mayan forest.  Meacham calls Sian Ka’an the “Mount Everest of Cave Diving.” 

Divers returning Cenote Yax Kai, Ox Bel Ha Cave System. Photo by Su Eun Kim.

“Sian Ka’an is pushing us geographically and logistically,” he explained. “It’s what Madden taught us early on. If you want to scoop booty, you’ve got to go where the booty is.”  CINDAQ also supports the Hoyo Negro Project, started by fellow GUE instructor Alberto Nava, which graced the cover of National Geographic in 2015, and was the subject t of a NOVA/PBS special “First Face of America,” which aired in 2018; Meacham teamed up with Madden for this project and was an assistant to the camera man and managed logistics. “I’m thankful for the opportunities that cave diving has afforded me,” he said.

Key to CINDAQ’s current efforts is a host of new imaging, digital data collection, and presentation tools and technologies to aid in the exploration and create public awareness. InDepth caught up with Meacham earlier this year to discuss the team’s latest efforts.

InDepth: Has CINDAQ lived up to your expectations?

Sam Meacham: Absolutely, yes, and beyond. It exceeded my expectations. We established CINDAQ for pretty practical reasons and then it just kind of took off from there. And at the outset we had funds from Nature Conservancy, National Geographic Society, private funders and also the Summit Foundation in Washington D.C. We are extremely grateful for all of their support, and the support of our incredible volunteer divers through the Mexican Cave Diving Project (MCEP), which Chris Le Maillot and Fred Devos set up. Without both of these men we wouldn’t be able to accomplish even a fraction of what we do here.

It’s like living in a dream. Sometimes you shoot for the moon and you get the stars. So right now, we’re getting out into the stars and, in fact, several galaxies away. 

I know that you’ve done an incredible amount of new exploration as well as going back and re-surveying the previous work of your team and others. Do you have any statistics that you can share with us

Yeah, exploration is one of our main focuses right now because of the massive amounts of development that are taking place around Tulum, where the majority of the cave systems in this area are located. We are concerned about development and how it’s going to affect, not only the caves themselves, but most importantly the aquifer and the water that flows through our caves.

To give you a perspective, in 2018, out of a total of 18,000m/59,000 ft of total survey, 12,000m/39,300 ft was new exploration, and 6,000m/20,000 ft was resurvey of existing lines.  By contrast, in 2019, we did a total of 80,000 m/262,000 feet of total survey; 30,000m/98,400 ft was new exploration and 50,000m/164,000 feet was re-survey. Then in January of this year, in just 14 days of diving, we resurveyed 8,445m/27,700 ft and explored 11,277m/37,000 ft of new passageway.  So, it’s kind of been growing exponentially.  And all of this is just in the Ox Bel Ha system.

So, what seemed like a preposterous proposal just a year and a half, two years ago: that we could resurvey an entire cave system the size of Ox Bel Ha, which is well over 300,000m/984,252 ft now, does not seem like such a crazy proposition anymore.

Amazing. I remember when I was coming up in the 90s, the Yucatan was regarded as the new frontier of cave diving, there was so much exploration going on. Now almost 30 years later, I am guessing much of the diving community, thinks, well it’s all been explored down there. And that’s obviously not the case. Any idea of how much remaining exploration there is to be done?

My response is a whole hearted, HAH! We’re still just scratching the surface. In fact, it doesn’t take much math, but you can figure out the ratio: for every one meter that we resurvey there’s just a bit less than one meter of line that gets explored. We’re going back into the caves and marking leads and getting into new areas and expanding the extent of the caves. That’s what we’re really most interested in because of all of the development happening at the surface. We really want to do a good job so we can show the general public and the landowners exactly what’s going on beneath them as accurately as we possibly can.

So just to clarify, we’re talking about new exploration in known cave systems, versus systems that have yet to be discovered.

Correct. Just as an example, we have been in the area of Ox Bel Ha we are diving right now for, I don’t know, the last two or three months. The last time we were in one of the entrances in this area was in 2009; I don’t think we’ve been in the other entrance since 2002 or 2003. No one has been in there. The reason we haven’t gone back is because it’s just really hard to get to. Development is a double-edged sword. On the one hand, it means more humans and more waste and pollution, but it also means new roads. 

We now have a new road that runs through the middle of the jungle that takes us to three separate entrances and gives us access to a whole section of the cave that previously required a 45-minute hike to get to. So, yes, we are revisiting areas that we were in before, but we’ve never had the time and energy and ability to explore them to their full extent. Most of the original exploration that was going on there was all focused on the main tunnel, the gravy, the easy stuff. Now we’re focusing on linking up different sections of the cave to make it one.

September 2019, Cenote Gemini, eagle eye view from above courtesy of the drone. Photo courtesy of CINDAQ.

I heard that you started re-surveying old lines to test out some new surveying technology, the Mnemo and the Ariane cave mapping software, I want to talk about those. But why have you continued to re-survey?

That’s right. We started resurveying a small portion of the cave in 2018. The real objective was to see if the Mnemo and Ariane were good tools for us to use. We concluded pretty quickly that they were.  The benefit is that by going in and re-surveying the caves, we’re not only shoring up the data that we already have, but we can compare the historical data to the new data we are getting. 

It turns out that our historic data really wasn’t all that bad, but we benefit from better GPS now. It’s a lot more accurate, so we can correct things. In some cases, the original line survey had errors, which then threw the rest of the data off. Perhaps the coolest thing is that we are going back into areas of the cave that we haven’t been to for years as a result of better access, as I mentioned, and the fact that we have maintained good landowner relationships.

Tell me about Mnemo.

Well, for us, it started as a pet project in 2018. We’re very fortunate to have Sebastian Kister here who developed the Mnemo and also Ariane, the software that Mnemo communicates with, living right here in the Riviera Maya. At the time, I had heard about Mnemo and Ariane and I thought, okay, perhaps it will help us to get a handle on all the data that we have and help us be more efficient with time both in and out of the water. 

The mnemo in use doing cave survey. Photo by Christophe Le Maillot

Mnemo is an ingenious and simple device that has an internal compass, an internal pressure sensor, so it can measure depth and azimuth, but perhaps the most ingenious part of all, is its ability to measure distance. That has always been a bit of a conundrum. The traditional means, of course, is knotting the line at fixed distances, but that leads to error, as it’s easy to lose count.

What Sebastian came up with is a wheel that looks a bit like a piece of pizza with slices on it, and it spins around. It has a white slice and then a slice with nothing in it at all, and there are two light sensors, which count the white slice every time, which is a known distance that goes by. You attach the Mnemo to the line, and swim the line, while the device records distance, depth, and azimuth. It takes a little practice, but it’s  not hard to master. Last year I think we trained about 20 people to use it.

So you can swim or scooter and it just records as you go?

Yes. Scootering takes a little bit more practice, and you’ve got to be really careful because, of course, it has an internal compass, so you have to be very careful with anything magnetic, like a scooter’s battery and other electromagnetic components, in order to not interfere with the accuracy of the compass. You can survey on the scooter as long as you have big passageways. This allows us to cover a lot of distance in one dive. 

Then you just connect it to the computer after the dive and it uploads the data to Ariane’s Line?

Yeah, it goes right in. You have to tell Ariane where the data starts, so, like any cave survey, you have to know where the tie-in data is. But as long as you know that, you can keep track of the lines that you resurveyed with the Mnemo, and within a matter of minutes you can easily enter a ton of survey data—boom—in no time at all. Normally, it would take quite a while to transcribe the handwritten cave survey data into Excel and then copy and paste it into another survey program, and then upload it. This process was also prone to errors. Mnemo is much more accurate than anything we were able to do previously. To give you an idea of its accuracy, we recently completed a massive 5,000+ meter loop.  The loop closure error was less than 1%.  We would have had a hard time doing that with a hand survey.  The Mnemo just makes a lot of sense. And it has really streamlined our process in and out of the water. 

Photo courtesy of CINDAQ.
Are you able to upload the old survey data into Ariane’s Line as well?

Yes. Sebastian made it so that we could import the original cave data into Ariane. It’s fantastic because it gives us a means of comparison. Like I said, our original survey was actually pretty damn good given that it was done 20 years ago often with 35 W halogen bulbs and a single person surveying out after a solo exploration dive. 

I’m actually really proud of the survey that was originally generated. Interestingly though, some of the most valuable information in our survey work is the comments, for example like what you are seeing around you, the geology, the navigation symbols, directional markers, those sorts of things that help you to navigate the cave. So, by resurveying we are really enriching the survey comments which has a lot of benefits to safety and our general understanding of the cave.

We are also benefiting from advances in technology. We’re going back into the passageways with better lights, better batteries, and better scooters.  We’re using open circuit side mount, back mount and also RB-80s (semi-closed rebreather) in back mount and custom sidemount versions.

We have a great deal of versatility depending on what the cave throws at us. Especially with the RB80s, we can just spend up to seven hours of true working time underwater and get a lot done.

And I see you are employing lots of volunteers to help with the work! 
January 2020, Mark Garland and Alison Perkins after a productive week of diving from Cenote Coca Ha. This was on the last day of diving and all safety stages and scooters were removed. Photo by Sigurd Bowitz.

As with everything in Global Underwater Explorers (GUE), it’s a team effort and we’re extremely fortunate to have the team of people around us that support us and make it all possible. We have this fantastic wellspring of divers through our partners, the Mexican Cave Exploration Project (MCEP) who have amazing skills and are seeking purpose for using those skills. This is one place where we can totally put them to work. It’s a bit like Tom Sawyer convincing his friends to paint the fence. We’re doing the same thing with cave surveys. In fact, I have divers that just came back from a dive with data for me. They’re totally into it. They are just loving it. 

The fact we are using Mnemo means that they can immediately see what they surveyed that day. Previously, with the manual survey, it would take hours to get all the data, and that was just a total pain in the ass. We’ve finally found the tools and we have this incredible army of volunteer divers who come here and help us achieve our goal. So that’s our main thrust at Ox Bel Ha, resurveying and exploring.

You have also been deploying drones and using drone software for finding new areas too, haven’t you? Talk to me a little about that.

Hah! We’re everywhere. We bought our first drone in 2017. And I’d like to call it the revenge on my parents who never bought me anything that was remote-controlled. Hence the drone.  I guess you can’t take the boy in me away.

Cenote Yax Chen, Ox Bel Ha Cave System. Photo courtesy of CINDAQ.

At the outset, we thought it was a pretty cool tool just to help us to have periscopic vision in the jungle. As you well know, the jungle here is extremely monochrome and flat. And even if you crawl just to the top of the tallest tree in the forest, you’re only a few inches above all the other trees. With a drone we can get above that and gain this incredible perspective of everything that’s down below. 

It’s unbelievable that the technology, as it is right now, enables us to discover and document cenotes from a perspective that previously would have required a helicopter or an airplane, which would obviously be prohibitively expensive. 

So last year, we applied for and received an enterprise license from a company called DroneDeploy based in San Francisco. It enables us to plan flights and create geo-referenced orthophotos of the surface. This allows us to have an accurate and up-to-date snapshot of what is happening on the ground and how it relates to what we are seeing in the cave.  Ariane and ArcGIS allow us to overlay all of this data on the cave.  I’ve been telling people it’s like Project Baseline, but in the sky. We can monitor a site and see what’s happening from year to year. DroneDeploy also has a rudimentary filter that allows us to see the health of vegetation which is immensely helpful in seeing where cenotes might be. Foliage around cenotes is going to be a lot healthier than the rest of the jungle simply because those plants have ready access to water. And it gives us a rough idea of elevation at the treetops which is another indication. Taller vegetation tends to be around cenotes.

We can also use DroneDeploy to create a three-dimensional model of the terrain. We are doing a lot of photogrammetry of underwater passageways, so what we are going to conceivably be able to do in the future is to take a three-dimensional model of the surface and merge it with a three-dimensional model of the cave and have a real virtual experience where you can literally fly over the jungle and then down into a cenote and into the cave that is below it.

Close up of overlay of cave data displaying depth over drone imagery. Photo courtesy of CINDAQ.
Augmented reality (AR) is something you all got to play with last year using the 360° Boxfish camera, right? The Oculus Go demo that you gave me was just awesome.

Yes, we had the opportunity to demo a Boxfish 360 camera last May, thanks to Russell Hughes of Boxfish Research. He put it into our hands and let us run wild.  The results have been amazing. Augmented reality is different from virtual reality because we are just going along for the ride, and experiencing what the 360 cameras see.  From an educational standpoint, this is a game changer for us. 

Watch a 360° Camera Cavern Dive in Mexico’s Riviera Maya

Photo by Michael Menduno/M2

The interesting thing is that even experienced cave divers are seeing things that they’ve never seen before. We don’t usually stare up at the ceiling when we’re cave diving, so giving divers that perspective is pretty cool. One of the most rewarding things I have been able to do is to take my octogenarian parents, who have always been very supportive of me and what I do, cave diving with the augmented reality goggles.

And enable them to experience what a cave dive is actually like!

I can show people videos and photographs, write articles or do documentary films about what it is we do, and the environment we go into, but nothing has come anywhere as close as really connecting people to our world than the augmented reality stuff. My father was actually brought to tears. So, in just thinking about non-divers and raising awareness about this hidden world, we get pretty excited. Part of CINDAQ’s mission is educating people about the aquifer.  And we’ve always had this incredible stumbling block helping people grasp what we experience when we go down there. We’re now convinced that we finally have a means by which we can educate people about the aquifer and the caves.

The amazing Sun Cave at the University of California San Diego’s Cultural Heritage Engineering Initiative (CHEI). This is as close to a Star Trek ‘holodeck’ that any of us will ever get. Photo courtesy of CINDAQ.
So for example, Mexican policy makers that are actually making policy that could affect the aquifer.

Correct, yes. For anybody that’s a non-cave diver, we can take them cave diving now without fear of them dying, which is good.

Always a good thing! 

Yeah, and let’s not forget the scientists that we work with as well. We’re using a lot of photogrammetry to create models of the spaces that we go into. However, to enhance that with the augmented reality footage is absolutely fantastic. We’re just in this perfect storm of really cool technology that’s helping us to tell our story and, more importantly, to tell the story of these caves and the role they play, in a way that we never have before. 

I’m not kidding when I tell people—and I say this almost on a daily basis—that I have never been more excited about what I do than I am right now. We are currently testing out all this cool stuff in Mexico, but there is no reason that it can’t be done in underwater caves all over the world to highlight the importance of groundwater. At the end of the day, that is the issue: our freshwater resources, since 20% of the human population depends on groundwater.

Have you seen any impact yet? Have you created awareness among the authorities there, the people you deal with, the locals, the policymakers? 

Yes, local authorities are obviously aware of the fact that the cenotes are a huge economic driver for this area, and the diving industry is strong here. So, I think they understand the economic benefit of cenotes. Where people start to get a little confused is the incredible extent and magnitude of these massive cave systems like Ox Bel Ha and Sacactun. 

But the idea, which started back in the early 2000s, is to show people the interconnectivity of everything. If you dump sewage in the jungle here, it’s going to come out in the ocean over here, and that’s not such a great thing if you want tourists to enjoy your beaches. 

We’ve worked really hard to raise awareness about the importance of the aquifer here. We’re still lightyears from understanding how it all works, but yes, we’ve had an impact by helping to make freshwater resources an issue here. It’s challenging because there are no rivers and streams here; people can’t see the water beneath them. So it’s that much easier to contaminate and pollute because it’s out of sight and out of mind. 

You have to enable people to see what’s going on!

Yes, that was the thing we realized early on; we had to find a way to bring the cave up to the surface so everybody could see it. We had to make people conscious of the fact that these things even exist, and that they exist on a massive scale that interconnect every single ecosystem that the tourist economy here depends upon. 

Blake Wilson in Cenote Far, Ox Bel Ha Cave System. Photo by Sam Meacham CINDAQ AC.

If we don’t take care of the aquifer, which is the common thread to all of these ecosystems, then we’ve killed the goose that laid the golden egg. This area accounts for approximately 12% of Mexico’s gross domestic product and it’s all tourist based. So it’s hugely important to the regional and national economy that this place be as sustainable as possible. That’s where it’s hard to gain traction with decision makers: to convince people to have a long-term vision for the area versus a short-term vision. 

Fortunately, we now have much better tools to engage the public and decision-makers and hopefully make people want to preserve and protect these incredible natural wonders that they can’t see. Nobody’s going to care about it unless they can feel something for it. That is our very difficult job; making people care about these incredible places underwater that are invisible to them.

That’s what gets you excited?

I lie awake at night thinking about the fact it’s not necessarily the things that we have found, it’s the things we haven’t found yet, the things waiting to be discovered that will be important to science. Whether it’s biological, paleontological, archaeological or hydrological, any kind of “-ology.” Those are the things that are so exciting. It’s the prospect of what we might find. 

You can find Sam and CINDAQ Here:

Website: www.cindaq.org

Instagram: cindaq_mexico

Facebook: El Centro Investigador del Sistema Acuífero de Quintana Roo

YouTube: CINDAQ A.C. 

Additional Resources

CINDAQ And DroneDeploy  

Ariane’s Line: http://arianesline.azurewebsites.net

Mnemo: https://www.youtube.com/watch?v=uHNfQYkH2NI


Michael Menduno is InDepth’s editor-in-chief and an award-winning reporter and technologist who has written about diving and diving technology for 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. He also produced the first Tek, EUROTek, and ASIATek conferences, and organized Rebreather Forums 1.0 and 2.0. Michael received the OZTEKMedia Excellence Award in 2011, the EUROTek Lifetime Achievement Award in 2012, and the TEKDive USA Media Award in 2018. In addition to his responsibilities at InDepth, Menduno is a contributing editor for DAN Europe’s Alert Diver magazine and X-Ray Magazine, and writes for DeeperBlue.com

Cave

Meet The British Underground

It’s cold, dark, you can barely see two meters in front of you, and you’re diving alone. Oh, and there’s a sump up ahead. Welcome to the British Underground! Not exactly a scooter-ride in the warm, clear, stalactite studded caves that lay beneath Riviera Maya. Here British caver and training officer for the Somerset Section of the Cave Diving Group Michael Thomas guides us on a tour of British cave diving and explains why it may not be everyone’s cuppa tea.

Published

on

By

by Michael Thomas 

Header photo courtesy Michael Thomas. Diver entering Keld Head in the Yorkshire Dales.

Recently someone approached me about British cave diving wondering what in particular makes it so very different from Mexican cave diving, for example, and why it’s so appealing to a select few. In the U.K. we have two types of underground diving. The first is the significant number of flooded mines that have given rise to some world-class mine diving that’s becoming very popular with technical divers from around the world. The second type of  underground diving is traditional British cave diving, which, due to the nature of U.K. caves, involves both dry caving and cave diving. The aim is to explore the caves underwater or in the dry underground following it as far as possible. We are now finding that technically trained mine and cave divers are starting to learn the art of dry cave exploration in order to further their knowledge and adventure, some even gaining enough experience to join the Cave Diving Group in the U.K. 

Firstly, a little about myself if I may be so bold. My diving career is now in its thirty-third consecutive year, from starting out as a trainee open water diver with BSAC to trainee cave diver within the CDG to becoming the Training Officer of the British Cave Diving Group Somerset Section in the U.K. Since 1996 I’ve had links to TDI and currently hold Full Cave Instructor, Sidemount and Tech Instructor status with TDI, active mod 3 CCR cave diver, and on the British Cave Rescue call out list as a diver. 

My diving life crosses all paths of British and worldwide diving, from open water to cave and tech. I’m actively involved with technical diving conferences and a fellow of the Royal Geographic Society of the U.K. My father was a cave explorer before me, and my son has also taken the same path. You could say, caves and diving are our lives. 

See The CDG 

To understand British cave diving we first need to understand the CDG.  The Cave Diving Group is the representative body for cave divers in Great Britain and Northern Ireland and is a constituent body of the British Caving Association (BCA). Its function is to educate and support cavers for recreational and exploratory operations in British sumps. The CDG also helps control access to numerous cave sites, including Wookey Hole and Gough’s Cave  in Somerset, and Keld Head And Hurtle Pot in Yorkshire, in conjunction with the BCA. The group was formed in 1946 by the late Graham Balcombe, and its continuous existence to the present day makes it the oldest amateur technical and cave diving organization in the world. Graham Balcombe arguably invented cave diving in the U.K. with his audacious dives in Swildon’s Hole cave and Wookey Hole cave in 1935. 

Now the huge difference between the Cave Diving Group and other cave diving training agencies is you can’t just sign up and pay to do a training course. From the very start in 1946, the prerequisite for joining the CDG was always and is a knowledge and experience base of dry caving skills, though in modern years we also require an open water certification. Once you have made yourself known to one of the four sections that make up the CDG—Somerset, Welsh, Northern, and Derbyshire—and proven you have dry caving skills and can get along with your new-found friends, you are voted in, hopefully to whichever section you approached. 

CDG rescue practice exercise after the Thailand rescue to update our rescue skills and standards. Photo courtesy of Michael Thomas.

As a trainee member of the cave diving group, the training is apprenticeship based and generally takes between 12-18 months. At the end of that, a written exam and an underwater test is completed, and as long as your section is in agreement, the qualified diver status is awarded. It’s a slow process but ensures adequate experience is gained in a variety of different sites and conditions, producing a cave diver that is capable of exploration cave diving, rescue work, and continued training of new members. 



The Solo Mentality 

Probably the one difference with most U.K. cave diving, that is a world away from agency standards, is the CDG approach to team diving. In all but a few sites in the U.K., the CDG considers solo diving the safest way to approach the dive. While divers might enter the cave together as a team, and dry cave their way to the dive base (dive site within the cave), once they are in the water they typically dive solo. This is because a diver is usually unable to help another diver in the water. Then they meet up on the other side if more dry caving is to be done. 

CDG trainee divers are taught from the beginning to be solo divers or work within a team as solo divers, something we call “team solo.” Most dive sites in natural caves in the U.K. are unsuitable for team diving. The few sites that are suitable for a team to operate together, such as Wookey Hole in Somerset, Hurtle Pot in the Yorkshire Dales, and Porth Yr Ogof in South Wales, should really be a team of only two divers. Passage size and visibility generally means divers can’t see the third team member if at the back or front of the team. The mine diving sites are much more suited to team diving with larger passages and clearer water. The links below offer more information on mine diving in the U.K. [Ed.note: Global Underwater Explorers does not sanction solo diving.]

Robert Thomas at Top waterfall sump dive base Ogof Ffynnon Ddu Cave Wales UK. Photo courtesy of Michael Thomas.

The article, “Solo Cave Diving,” on the CDG website explains why it recommends solo cave diving as the safer alternative for U.K. sump conditions. It lists some of the advantages of solo cave diving as follows:

  • There’s no one to get physically jammed in the passage behind you (thereby blocking your exit).
  • There’s no one behind you who may get tangled in the line and have to cut it—leaving you with no guide home.
  • There’s no one to accidentally disturb your ‘out tags’ at line junctions (e.g. in one cave there are 10 branch lines off the main line in the first 500 m/1640 ft of passage).
  • There’s no one to cause silt problems (but yourself).
  • There’s no chance of being called upon to share air—in small passages.
  • There’s nothing to get confused about—communication in sumps varies from difficult to impossible.
  • There’s no one to provide you with a false sense of security.
  • There’s no one to worry about but yourself, so you can concentrate on your own safety.

Equipment Configuration

Due to the generally small passage size of British caves and the sometimes energetic nature of transporting equipment to a cave dive base (station), sidemount diving is the normal equipment configuration. Sidemount started in the U.K. in the 1960s with a need for streamlined and lightweight diving equipment. U.K. cave divers today will have a choice of sidemount harness for the project they are involved with. In a short, shallow, or constricted dive, the diver will use a wetsuit and a lightweight, webbing-only harness with no buoyancy, as it’s not needed if your chest is on the floor and your back on the ceiling. 

 Diver leaving Dire Straits dive base Gough’s Cave Somerset UK. Photo courtesy of Michael Thomas.

In slightly larger cave passages, the modern British cave diver will use one of the now-common sidemount harnesses that are available. Many British caves require vertical cave techniques to reach the water, so the divers have modified the sidemount harness to be able to descend into the dry cave, do the dive, and then climb out. It’s very rare to find a British cave diver with an unmodified sidemount harness. For exposure suits, many short dives and some longer dives, if significant dry caving is expected before or after, the dive will be done in a wetsuit even though water temperature is on average between 7-10 degrees C/45-50 degrees F. This is for practical reasons, as it’s very difficult and potentially dangerous caving in a drysuit, so better to be slightly chilly during the dive and caving safely. 

For larger sites and when the diver is expected to be underwater most of the time, a drysuit is sometimes carried to the dive base and put on underground, to be utilized for the dive. As most divers are solo diving, having two short standard-length hoses on their regulators is normal, although for team diving or cave rescue, a standard long hose is used on the right. 

British cave divers always use helmets, as they provide protection from the environment in the dry caves as well as underwater, and are a great place to carry lights. Hand-held primary lights are used in larger, clearer passages with the helmet lights in reserve. For dive lines, we use 4 mm thick lines as permanent dive lines and we have fixed junctions in all caves— no jumps or gaps. Standard line arrows and cookies will not fit on a U.K. line. Pegs are used, or permanent markers on junctions to show the way home. It’s very unlikely you will see another dive team in the cave on the day you are visiting, and following a thicker line in sometimes low visibility and cold water is much safer and more comforting than trying to follow a technical diving line. 

Exploring U.K. caves 

The raison d’etre for the Cave Diving Groups formation was and still is the exploration of caves, including the surveying and reporting of that exploration and the training of new divers. The CDG publishes a journal four times a year with exploration reports and many books on the subject of U.K. caves and techniques. If it’s not surveyed and reported, it’s not explored. Now, it would be extremely tedious to the reader if I listed all exploration in underwater caves in the U.K.—we have thousands of reports—so I’ll mention a few of the classics to set the scene, and remember all exploration can be researched in the CDG journals. 

If visiting, most U.K. cave divers are happy to show you around or even get you involved in projects, although they will be of a very different style of exploration than found in Bahamas or Mexico, for instance, where swimming into hundreds of metres of new cave is possible. Big breakthroughs in the U.K. are rare, and if a diver explores 10 m/33 ft of new cave with ongoing passage seen, they will be happy. 

Wookey Hole Cave Somerset, Somerset 

Exploration in the home of British cave diving started in 1935 and carries on to this day. Slow and determined work by some of the great names in cave diving, including Balcombe, Martyn Farr, Rob Parker, Rick Stanton, and John Volanthen have seen this multi sump cave reach 90 m/294 ft depth beyond chamber 25 in extremely committing passages. Smaller side passages throughout the cave are still being explored. 

Michael Thomas surfacing in Wookey Hole after Recovering a 3rd 4th Century Roman pot ! Photo courtesy of Michael Thomas.

The Llangattock Cave Systems, South Wales 

Under Llangattock mountain lies many kilometers of caving—two caves, Ogof Daren Cilau at 27 km long and next door Ogof Agen Allwedd at 32.5 km, provide access to many cave diving sites that have provided incredible exploration over the years and will hopefully provide more in the years to come. One of the longest dives in the system is the Pwll y Cwm resurgence at 630 m/2066 ft long, surfacing in the downstream end of Daren Cilau. 

Kingsdale Master Cave and Keld Head, Yorkshire Dales 

One of the true classics of world class cave diving is the Kingsdale to Keld Head system. Graham Balcombe, of Wookey Hole fame, conducted dives in 1945 in Keld Head, and in 1978, Geoff Yeadon and Oliver Statham broke the world record with an 1829 m/6000 ft dive between Kingsdale Master Cave and Keld Head, connecting the two caves. In 1991, the underwater system was further extended, linking it into King Pot cave access to the valley floor, a traverse of 3 km in British conditions. Today, divers continue to explore and extend this system. 

Speedwell Cavern Main Rising, Derbyshire Dales 

This dive site requires a reasonable amount of dry caving effort to reach the dive base. The dive itself is multi-profile with a descent to 36 m/118 ft then up to 2.5 m/8 ft via a constricted rift, then finally down to 71 m/232 ft at the end. In the 1980s John Cordingley and Russel Carter worked the site and finally, 71 m/233 ft was reached by Martin Groves in 2002. The way on was lost in boulders and boiling sand with the water surging upwards. This was confirmed by John Volanthen in 2006. A change in geology and future technologies await. 

The Green Holes of Doolin, Ireland 

In the years leading up to the 1980s, open water divers reported cave entrances in the sea on the Doolin coast. These completely submerged caves are extremely weather dependent due to taking the full force of the Atlantic Ocean. But after experience gained in the Bahamas’ Blue Holes, British divers tried their luck exploring what became known as Green Holes. Several sites including Reef Caves, Hell Complex, Urchin Cave, and the longest Mermaid’s Hole have had successive and continued exploration. 1025 m/3350 ft penetration being reached in Mermaid’s Hole by Artur Kozlowski. Exploration continues when the weather allows. 

Robert Thomas demonstrates vertical caving skills needed to reach many cave diving sites in the UK. Photo courtesy of Michael Thomas.

Swildon’s Hole Cave, Somerset 

A true classic sump diver’s cave with long sections of active wet streamway takes the visitor down to a series of eight short sumps that require diving and more caving to reach the terminal sump and end of the cave at Swildon’s 12. Wetsuits and lightweight sidemount harness and small cylinders needed. A grand day out. 

Porth Yr Ogof Cave, South Wales 

One of the finest and reasonably easy physical-access cave dives in the U.K. The dive starts from a small pool after a short climb down between boulders. A shallow and comfortable passage winds its way up the valley passing Rawlbolt Airbell 150 m/492 ft from base and Four Ways airbell around 200 m/656 ft from base. At 250 m/820 ft from base, a cobble squeeze can be passed to the surface in the dry upper cave. The flow in this cave can be very high and the passage size varies from 1 m wide to 3 m wide, making progress upstream interesting and downstream on the return exciting. 

Hurtle Pot, Yorkshire Dales 

Probably the most dived cave in the U.K. due to its easy access and the possibility of longer dives upstream in a large passage towards Jingle Pot Cave and an area called The Deep reaching 35 m/114 ft depth in a low complicated passage towards the end around 460 m/1508 ft from base. Downstream a 400 m/1312 ft long traverse can be made to surface in Midge Hole cave reaching 20 m/65 ft depth on the way. This cave floods dramatically in bad weather, and constant line repairs need to be made by local CDG divers. 

Peak Cavern, Derbyshire Dales 

Peak Cavern is an extensive dry cave with several significant cave diving sites located within the system. The resurgence is a classic training dive in a lovely bedding plane style passage reaching the surface in the main cave. Ink sump within the cave, nearly 200 m/653 ft long, leads to Doom’s Retreat, an area worked by Jim Lister and the most extensive digging project to find a new cave beyond a sump in the U.K. Far Sump at 385 m/1263 ft long leads to an extensive dry section of cave with some extremely technical caving that can now get you to surface on the hills above. 

Pollatoomary Resurgence, Ireland 

Not many easy surface access cave diving sites that go deep are to be found in the British Isles, but this one in Ireland is one. A resurgence site that reaches 103 m/336 ft but in dark, unfriendly waters. Original exploration by Martyn Farr in 1978 and taken to 103 m by Artur Kozlowski. 

Divers leaving surface in Wookey Hole on a practice cave diving rescue.  photo courtesy of Michael Thomas.

In summary, British cave diving is historically one of the oldest branches of the sport of cave diving. The Cave Diving Group’s knowledge and standards and procedures evolved over the years to the safest method to explore or dive in U.K. style caves. It is not diving in Wakulla Springs and does not pretend to be, although several CDG members got involved in the early Wakulla expeditions. It is at times cold, wet, and unpleasant, but also can be extremely rewarding, with new caves found or just a superb dive in excellent conditions. U.K. style conditions can be found all over the world—think of the Thailand Rescue in 2018—and it’s in these conditions that the CDG system is at its best. If you’re wanting more information on the CDG or sump diving and vertical access sump diving, please give us a shout. Just remember—a pint of English beer is supposed to be warm. Stay safe and dive well. 

Additional Resources:

Website: The British Cave Diving Group

From GUE’s membership magazine QUEST: “British Cave Diving: Wookey Hole and The Cave Diving Group” by Duncan Price

Books about British cave diving:

A Glimmering in Darkness by Graham Balcombe 

The Darkness Beckons by Martyn Farr 

Interview with Cave Diving Legend Martyn Farr

Historical British cave diving films:

Trailer for documentary film ‘Wookey’ by Gavin Newman

The Underground Eiger (1980s)

Articles by Michael Thomas:

Slow Down Young fellas-Attitudes in Technical Diving

The Difference Between Caves and Mines

Mine Diving in the UK


Michael Thomas’s diving career is now in its 33rd consecutive year, from starting out as an open water diver then a trainee cave diver to becoming the Training Officer of the British Cave Diving Group Somerset Section. He is also a Full Cave Instructor, Sidemount and Tech Instructor with TDI, active mod 3 CCR cave diver, and on the British cave rescue call out list as a diver. 

Thomas is heavily involved in U.K. diving projects and training, plus overseas diving and caving. Diving is life or is life diving? 

Continue Reading

Subscribe

Submerge yourself in our content by signing up for our monthly newsletters. Stay up to date and on top of your diving.

Thank You to Our Sponsors

Education