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by Justin Barbour
Header photo by Justin Barbour
There is always one style of diving that most divers are quick to avoid: Cave Diving. It has developed a reputation as being one of the most dangerous styles of diving in the world, and the divers who do it regularly tend to be categorized as insane. This was definitely my thoughts when I initially signed up for my cave diving class. I was constantly told that cave divers were tempting mother nature to flick them into the afterlife at high speed.
So why sign up for a class that you’re scared of? I was looking for a new challenge. After one of my teammates returned from Mexico from his first cave class it was all he could talk about. I joined him in Florida at the GUE Conference last year and decided to test the waters out in Ginnie Springs at The Ballroom. The moment I passed through the opening and saw the whole room open up I was hooked. The feeling of being able to overcome the fear of the unknown was something I truly never thought I would be able to do and it was incredible. Swimming around the room and looking at the rock work, exploring the cracks and crevasses, experiencing a new kind of darkness, it can easily be seen how addicting this could be. The next day my teammate Fred Espino and I signed up for our Cave 1 class in Mexico.
We trained for months diving as often as we could both during the day and night to simulate the feeling of being in a cave. Running line around rocks, a seemingly endless number of valve drills and s-drills, and fine tuning our positioning kicks to make sure we were ready to hit the ground running when we arrived. After every dive I caught myself thinking “are we really about to fly to Mexico and hop into a cave?” I asked myself that question even right up to the point of throwing my carbon fiber backplate into my pelican case the day before my flight.
Once in Cancun, it’s about an hour-long drive to Zero Gravity (ZG). At times the roads can feel a bit like Mario Kart brought to life, but it only added to the sense of adventure we were embarking on. Once we arrived at Zero Gravity, we were immediately introduced to Christopher Le Maillot and Fred Devos, the two owners of Zero Gravity. Between the two of them they have an uncanny ability to make you feel immediately at home.
There are early mornings at ZG. Before the sun rose on our first day we were up and working on our gear. We had dives planned that day to get acclimated to diving in this new environment and some last-minute rehearsals on skills. We arrived at the Dream Gate cenote and were in awe. We briefed and got our gear together with our guide as fast as possible and climbed down the ladders to get inside of the cave. Once in the water, trying to take in this wild moment in our lives, I realized that any notions of fear that I had were completely gone. It was only the giddy feeling you feel as a kid coming down the stairs on Christmas morning.
As we descended into the cavern, we quickly realized how people can get hurt. Caves are the darkest places on Earth, and yet inspire a sense of wonder. As our can lights cut through the darkness, they begin to reveal the true beauty of the cave. The speleothems, or decorations, are some of the most magnificent parts inside of the caves in Mexico. These stalactites and stalagmites are remnants from when the cave was dry before the last ice age. As we swam through the cave, we realized that we are truly swimming through a frozen moment in time. Looking at the walls you can see the different types of rock layers as they were built up over tens of thousands of years.
The next morning, we got to meet our instructor Laszlo Cseh. We spent most of the first day in the classroom going over theory, the history of cave diving, and the basics for why the rules are set in stone. Laszlo seemed to have an endless supply of examples for these rules in real life scenarios which seemed to be calming rather than alarming to us. That afternoon we drove to our first cenote Xtabay where we got to run through safety drills and such to make sure our fundamentals were down before running our first line into the cave. After a few practice runs in the open water portion it was time to try our first line run into the cave.
The cave initially opened up into a massive room with an enormous triangular rock in the middle of it from the last time the roof collapsed. Once we got to the top of the rock, we were able to tie into the main line and do our initial checks of gas, time, and a quick flow check. Laszlo however had other plans for us. Running up and down the line practicing our kicks to make sure they were perfected for our first official cave dive the following morning. Even that little rush of running the line from open water to the main line was amazing.
The following morning, as with every morning, we were up and downstairs bright and early analyzing our tanks and making sure our gear was good to go so we could get to the cenote first. Upon arrival we quickly set our gear up, listened to the briefing by Laszlo, and walked back into Xtabay for our first official cave dive. Fred ran the line in this time and made quick work up to the main line. From there we were able to proceed into the cave.
One of the first things we realized when in the cave is the vastness of it. Shining our lights ahead we couldn’t see where the end of the beam was, even with crystal clear water. Once we left the entrance, we immediately came to what is known as a Halocline. This is where the saltwater in the bottom of the cave meets with the freshwater creating a false ceiling. As you pass over it, it looks like you’re swimming over a pool inside of the cave. This is something that can play tricks on the mind particularly to a disorientated diver on heading out of the cave.
As we swam through it the fresh and saltwater began to mix clouding the visibility to near zero. Once we staggered on either side of the line however we were able to maintain visual contact with each other, the line, and were able to enjoy the 86ºF/30ºC saltwater that we just dipped into.
The colors in the cave were incredible. The blues and greens were striking as our lights slowly moved about the cave. The rock walls were white in the saltwater, and a tan color in the freshwater.
As we moved room to room, I glanced at my computer and realized we’d been swimming for 30 minutes. While that’s not an unusual time for an open water dive, I rapidly came to the realization of “wait, if something goes wrong, we’re going to have to turn around and swim at least another 30 minutes to get back out.” It was this sobering thought that helped me understand the severity of what we were doing. Nothing a few glances around the cave couldn’t snap me out of the thought and continue on with the dive.
As we continued to swim, we came upon a bed plane section of the cave. This is where the cave narrows, but not too small, vertically and can stretch for hundreds of feet horizontally. As we swam forward, we truly started to feel like cave divers. Alas only a few minutes into the dive we hit our turn pressure and had to exit the cave.
As we surfaced Fred and I immediately popped our regulators out of our mouths and exploded with excitement. It seemed like months of hard work and uncertainty finally paid off in that moment, and it was only day two of the class. Laszlo, in his usual Laszlo calm and collected nature, reigned us in with a subtle, “Meh it was ok, let’s see how you do in the cave.” Little did we know the gauntlet that was ahead of us.
Throughout the class we would arrive first thing in the morning, set up our gear, run through dry drills, gear up, and do three to four dives in a day. Upon finishing those we would drive back to ZG and would be in theory for a few more hours before finally being sprung loose for tacos at Marre Marre across the street. They were very long days to say the least, yet every morning we would wake up before our alarms and couldn’t wait to see what the next set of dives had in store for us.
The next few days were filled with every failure that Laszlo and his trusty bubble gun sidekick could think of. From light failures (primary and both back up lights), to regulator failures, we drilled until it became second nature. On one particular dive we were particularly tested. As we swam through the cave just as we were passing through a thermocline I had a simulated primary light failure. After going through the procedures for stowing, deploying backups, etc. Fred and I turned the dive and started our exit. Suddenly he also experienced a simulated primary light failure and had to go through that process. One thing after another happened honing in our focus to the point where we found ourselves in total darkness. As we stayed in touch-contact we moved along the line as a unit. This shows a level of trust in not only your training, but your teammate as well.
Though as the days went on our confidence began to grow swimming around in the caves. Our awareness began to expand to allow us not only to focus on the team, but also begin to actually see the cave. Looking for the jump lines off the main line, seeing more of the details in the room, genuinely being able to take in the vastness and natural beauty that helped shape these caves over millennia.
On the final day we were tasked with two of the most important skills a new cave diver can learn: lost line drill while blindfolded, and gas share exit while blind. These are skills that hopefully a diver never needs to use, however we are going into a hostile world every time we enter a cave, so it’s important to train for every scenario to be prepared for whatever is thrown our way. In a strange way having the blindfold on elicited a sense of calm like I’d never felt. One hand on the line, the other out in front feeling our way out, with Fred hanging onto my elbow, we moved as a unit through the cave, navigating each station (tie off on a rock) as we moved. It felt like a new puzzle each time we came to a station as we moved our way out.
By the end of the day, Laszlo decided that we’d been through enough and we officially were Cave 1 divers. The feeling was hard to describe for a number of reasons. Chiefly both Fred and I had finally reached the moment we had been training for, studying for, and fearful about. We passed. We were officially apart of that group of divers most people think have a screw loose.
Looking back on what we learned and experienced, it’s clear to see that there are really only a few hard-fast rules to follow, similarly and readily transferable to open water dives, which minimize the risk we take on in the caves. First, plan your dive and dive your plan. This includes careful gas planning, and everyone taking responsibility for their own gear, gas, and navigation. Having a continuous guideline starting in open water, so that even in zero visibility you can always find your way out. Maintain your equipment making sure all regulators, valves, and lights are in prime shape to avoid potential problems in the caves. And lastly, ALWAYS be aware of the mainline. With these in mind one can go around the world swimming through the history books in caves and mines exploring what once was and embracing the beauty of what is.
Diving since 1998 from the Maldives to the Midwest, Justin is a PADI Master Scuba Diver Trainer and GUE Diver who brings a courageous mentality and humorous demeanor to the water. From 2015-2020 he spent countless hours volunteering at the Aquarium of the Pacific applying his expertise to educate children on sustainable ocean interaction.
As a boy he would read constantly about marine biology, wanting to see it for himself he dove right in and has hardly been up for air since. Most intriguing to him is exploring and learning the history of shipwrecks. Justin’s life above sea level includes a career path that has taken him from medical sales to tech startups, every endeavor inspired by the tenacity of being a former collegiate athlete. His goal is to never stop pushing himself, allowing the water to continually reveal character and to share those experiences with others.
They Discovered an 11,000-year-old Submerged Ochre Mine
The exploration crew at CINDAQ, headquartered at Zero Gravity Dive Center in Puerto Aventuras made international news this year with their discovery of an ancient submerged ochre mine. Fortunately, they were happy to share the secrets of its discovery and how they documented their find with British cave and 3D photogrammetry instructor John Kendall. Oculus Rifts anyone?
By John Kendall
Header image courtesy of CINDAQ
In 2017, underwater cave explorers Fred Devos, Christophe Le Maillot, and Sam Meacham found evidence of ancient mining activity while exploring and mapping new tunnels of an underwater cave near Akumal, Quintana Roo, Mexico. Historians know that ancient residents actively mined pigment and other minerals from the caves of the Yucatan Peninsula, but the ancient mines the CINDAQ team discovered are now submerged, indicating that such mineral exploitation occurred thousands of years ago.
At the end of the last Ice Age, intrepid miners ventured deep into these tunnels with torches in hand. The navigational markers, mining debris, fire pits, and excavation pits they left behind are now entirely underwater. Over the last three years, the three explorers (along with others) have been surveying the site and making 3D photogrammetric models of the mine workings. As the mine has been submerged for around 8,000 years, it’s been untouched since then, and it’s an amazing time capsule. The project recently hit the international news when the first results were published. I was pleased to be able to chat with Chris, Fred, and Sam to find out a bit more about the project, and the challenges faced with archaeological work in a cave environment.
John Kendall: How did you happen to find the mine?
Chris Le Maillot: As always, there was a little bit of chance involved with it. The cave—Sagitario, which is a beautiful cave behind Minotauro—was initially explored by a few local cave divers. They established an upstream and part of a downstream, dropping down in the upstream to around 22 m/72 ft, and there’s the halocline sitting at that depth. It’s not always the case, but they didn’t take any survey, absolutely nothing. So I don’t think the information was there for them to continue on with the exploration. As you know, once you have that data in and have a good concept of what the cave is doing and where it’s going, it’s easier for you to poke around and find potential continuations of the cave passages.
So one of the divers asked Fred [Devos] to get involved to create a survey. That comes from the fact that Fred previously had done some mapping for these guys. Fred had a cave survey class coming up, so he took the class there, and spent the week with the survey class mapping the downstream part. Obviously, when they got to the end of the line, Fred could see that there was potential for further exploration. But you can’t really go off exploring during a class, so he went back with Sam [Meacham].
So then you went back and explored?
Fred Devos: Exploring caves is what we’ve been doing for more than 20 years, and so it’s a regular event during the mapping of a cave to find more cave to explore. You know, when mapping, we have to swim off to measure the side walls, sometimes there isn’t a wall, and then end up exploring that passage. I was in the process of making a detailed map of this cave, and found this passage, so I went back with Sam, and we immediately realized something was unusual. Things were out of place, we started seeing rocks piled on top of each other, speleothems in places they shouldn’t have been, and the further we went the more of this we saw.
“Exploring caves is what we’ve been doing for more than 20 years, and so it’s a regular event during the mapping of a cave to find more cave to explore.”
We started picking up a little bit of flow, which is always a good thing in exploration, and that led us to this restriction, where all the water was going through, and I don’t think we’d have made it through if the restriction hadn’t been manipulated before we got there. So, you know, speleothems were smashed out, and it really looked like 100 divers had gone through there before us, which really piqued our curiosity as we knew no one had been there before us. We happened to be in back mount during this dive and I managed to squeeze through there and called Sam through, and that was when we first saw irrefutable evidence of what humans had been doing in this cave—you know, pre-8,000 years ago.
“It was pretty clear to anyone what we were seeing, that people had been digging in here, smashing open the floor and pulling out huge amounts of sediment and piling stuff out of the way. It was super exciting.”
We didn’t have to wait for lab results to come back or ask an archaeologist about it. It was pretty clear to anyone what we were seeing, that people had been digging in here, smashing open the floor and pulling out huge amounts of sediment and piling stuff out of the way. It was super exciting, as it was something we’d suspected for quite a while but had never really determined for sure that was what we were seeing. But this time it was obvious, and there was no question about it.
So, how large an area does the mine occupy?
Sam Meacham: It’s about 250 m/817 ft of cave passageways that are exemplary of the mining activity, and everything we’re seeing there shows the things that people were doing in the mine.
Devos: And we haven’t finished exploring yet. There are hectares of mining area, so it’s not just one hole that’s been dug out. It’s entire passages and we’re talking about hundreds, maybe thousands of tons of material, and remember we have dates spanning maybe a 2,000-year period.
What makes La Mina so significant from a scientific point of view?
Devos: The amount of workings means that this was a massive undertaking. Not just the mining itself, but it’s clear it wasn’t just a one-person adventure. It must have been multi-generational, but beyond that it speaks very much about the organization of the people of that time. So as you can imagine, they were in a dark cave and needed fire for light. So they needed people to bring in the firewood, and others to cart out the material, and there were probably explorers at the time. You know, people that ventured further into the caves away from the exit into the smaller passages…to find this very valuable resource. And I imagine they were the ones that were being punished somehow because the risk involved was probably much greater. So, you know, if they didn’t do their work well in the mine, they probably got sent to explore.
So are there any archaeological signs on the surface around the mine?
Devos: Well there probably are, there’s certainly Maya era archaeology, and in almost every cave we see evidence of that, but we’re talking about 5,000 years ago. The mine was even further back, so anything that was once there won’t be anymore, and the only place we are likely to find anything is in the caves.
Let’s chat about the photogrammetry side. More and more people are hearing about photogrammetry, but I think the readers will be interested to hear a bit more about the challenges that you faced doing photogrammetry in a cave environment, where everything around you is archaeological.
Meacham: I think that can get us started on an interesting concept. In 2010, Chris, Fred, and I, Beto Nava, as well and Franco Attolini and Danny Riordan and Roberto Chavez, all did our underwater archeology course here in Mexico with the Nautical Archeology Society that was supported by the National Institute of Anthropology and History (INAH). It empowered us.
And by having that NAS certification, it kind of helped check a box for the Institute. And, you know, they could say if anybody questioned our abilities, well, we’ve got the certification.
I’d say the genesis of this for all of us here was the Hoyo Negro project, and with the exploration followed by the high grade survey, and then the photogrammetry, which is another whole level in itself. The major problem in Negro is the pit itself—it’s just immense—and how do you document something like that? So we worked with Beto and the team who came up with a grid system at 34 m/110 ft depth, and then it’s every 0.8 m/2.5 ft with a cookie on the line, and so it’s a systematic grid. The difficulty there is that it’s not just a nice flat bottom, it goes from 40 m/130 ft to about 55 m/179 ft, and it just becomes really complex.
But basically what I’ve been doing there is assisting with the lighting or helping Beto. So when we jump forward to doing the mine, it’s a completely different environment. There’s no pit—it’s a continuous cave—so there was no way we could put in a grid, and I’ve never really done photogrammetry before. I had observed it being done, but I was starting from scratch in terms of my own experience. So it was a challenge, but I had plenty of people to go to as resources, and who could check out what I’d done and help make it better. And what’s interesting about the big model is that you can see my progression as we go around, and now of course I want to go back and do it all over again.
So in terms of the challenges, I bought a Sony A7S camera and a Nauticam housing for it, and we just went in and started taking a bunch of photographs, came back, and put it into Agisoft. I have to say my expectations were low, but we were all pleasantly surprised when the model came back. This is like, “Wow that’s what we’re actually seeing there,” and it’s so cool. So that gave me the confidence to say, “I think I can do this,” and we basically picked about 250 m/817 ft of cave passage, which is a great example of the mining activity and of seeing what people were doing there.
That sounds like quite a learning curve, and a big challenge.
Meacham: Yes, we just started going in and piece by piece doing sections of the cave. I can’t remember how long in total we were down there. I’m sure it’s written down somewhere, but we took something around 18,000 photos. And as you know, taking the photos is probably the easiest part. Having the computing power and post-processing of the images is the key. A lot of people treat Agisoft as a bit of a black box, but you know it’s garbage in, garbage out. So in terms of the environment, we’re talking about a ceiling height that’s minimal, and while you can fit through OK, you want to be as high as possible for the photogrammetry in order to cover more area.
“I’m sure it’s written down somewhere, but we took something around 18,000 photos. And as you know, taking the photos is probably the easiest part. Having the computing power and post-processing of the images is the key.”
So, we just worked section by section, using the line as a reference. I was going down the line and started by making sure that I got any markers on it, and then going back and forth to get all the photos. The person that suffered the most was whoever was assigned to dive with me, as they just had to sit there and watch me go back and forth while taking the photos.
18,000 images! That’s a whole lot of processing.
Sam Meacham: Yes, we’re lucky to have the guys at University of California at San Diego (UCSD) helping us with the processing. I probably started off taking too many photos, but the computer guys complimented us on the photos and the overlap and coverage.
So what about other survey techniques, was there anything special about mapping this site?
Devos: We surveyed the first part of the cave, and that was pretty normal, but once we found the mine, then suddenly we had a need for all these new types of symbols that didn’t exist before for cave survey. I tried to think about what would be interesting to make notes of, but I didn’t want to speculate as to whether something was a natural pit or whether it was digging.
So we came up with three new symbols. There was already a symbol for a pit, but we added a jagged line on the pit to show that there was a broken edge, so it was smashed. Then we came up with a symbol for a displaced object, so if you see some stalactites and there was no way it came from the ceiling above, then that’s a displaced object. And then if you have stacked objects, so objects placed on top of each other, we had a symbol for that. We then made all of these colored red. I chose red because of the extracted material, the ochre. Also, when you look at the map, and you see all that red, it really shows the extent of the manipulation of the cave. It really brings it out, and I think that’s the most important thing about this cave. Sidewall information is nice, but this is very much an archaeological site.
So what’s next with the site? Any further diving plans?
Devos: We have some plans in place. The map that we’ve made, the photogrammetry, and the video documentation, even the exploration are not finished. So we actually concentrated on one area and tried to get that in the bag, you know, and focus our studies and our samples in that area, without stretching too far, but there’s still a huge portion to go. The technology really helps here, because you can bring that information out for the scientists and others to see. And then there’s much less need for others to go back there.
And this is really the part where we don’t know what’s going to happen. Are divers one day going to be able to go there to tour this site? Luckily, I’m not the one who will be making that decision; there is an archaeological department in Mexico who set the rules. But these conversations are starting, and we’re not really sure where they will lead. But for now we are doing what we can to secure the documentation of the site and working closely with the archaeologists and the landowner.
So a last question: What would your advice be to a diver who is just starting out on their GUE journey, and who hears about this and other projects, and wants to one day join?
Devos: We have been running all kinds of projects down here for years: exploration, science, surveys. Come and get involved, and help out. Good basic training helps open up the door.
Meacham: Once you’ve trained and gained enough experience to become confident in whatever environment you’re interested in, then come and get involved. There’s great training with the GUE Documentation Diver program, Science Diver, Photogrammetry Diver, and Cave Survey where you can actually put these skills to the test. Everyone on a project is an important part of making it work. Obviously it becomes tricky when archaeology is involved, as there can be federal laws and regulations that restrict access, and so we can’t always put just anyone onto a site, but there are all sorts of projects within GUE to help develop those skills and get known by project leaders.
Le Maillot: Of course, project diving is what GUE has been known for since the very beginning. So I think making that initial step to take training with GUE is an important one in the right direction. That’s the starting point of understanding how we are organized, the procedures that we use, [and] the team aspects of all our diving. And then it’s about thinking about what you want to do.
“Of course, project diving is what GUE has been known for since the very beginning. So I think making that initial step to take training with GUE is an important one in the right direction.”
If you’re interested in wrecks, you have Mario Arena in Sicily or Richard Lundgren with the Mars project, and you’re naturally going to be headed down the Tech 1/CCR route. If it’s the stuff in Florida, or Bosnia, or here in Mexico, and the cave thing really rocks your boat, then that’s where the GUE cave training comes in. Then, as you progress with your tech or cave training, you will get to know divers who are involved in projects, and that could be your instructor. You know, if you come here to do some cave diving in Mexico, then Fred is going to mention a few things about survey and cave projects in Mexico and around the world. So that will start opening up a different perspective for you.
Watch a Video of the Mine on GUE.tv. (Requires a GUE.tv membership or signing up for a free trial)
For more information about the La Mina project, you can visit the CINDAQ website
Check out the CINDAQ YouTube channel
John Kendall is a GUE technical, cave, and CCR instructor living in the UK. Since he was a small child, John has been fascinated by the underwater environment and the possibilities of adventure, and he is grateful to GUE for helping him to turn those childhood dreams into reality. As an instructor, John regularly travels around the world teaching GUE classes and helping to build local GUE communities. For the last 5 years, John has been working with underwater 3D Photogrammetry as a technique for nautical archaeology. This cutting edge technique allows for digital 3D models to be created of shipwrecks and caves, and allows researchers and scientists unparalleled abilities to manipulate and navigate the sites from the comfort of their own computers. John was the primary author of the GUE Photogrammetry class. He is also a member of the GUE Training Council and a Fellow of the Explorers Club.
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