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By Natalie Gibb
Header photo by Natalie Gibb
I squinted my eyes against 30,000 lumens of blinding light aimed directly into my mask. Somewhere in that burning star was my model, hovering expertly below crystalline stalactites, fragile as glass. I had schlepped seven lights into the passage and balanced them precariously around the chamber where they would not leave marks on the cave. It was beautiful, but after a few minutes, neither of us could see very well.
Considering that cave diving is a navigation-intense style of diving, it makes sense that temporarily blinding oneself with bright lights while engaged in a task-loading activity such as photography can have disastrous results. In this case, I managed to back over a jump line while repositioning myself. When the shot was finished, I turned into the cave along the jump line, thinking I was turning into the direction of exit. I glanced at my compass (a habit whenever I make a turn) and looked at the cave in front of me. Whoops, wrong direction, wrong formations! I thought to myself, and finished turning back to the mainline. There was no incident, just a split second moment when I turned the wrong direction, thinking I was pointed to the exit.
Yet, how many cave divers visiting Mexico’s caves know the lines as well as I do? My tiny mistake had zero negative consequences because I was shooting in a cave I have dived well over 100 times. I recognized the jump line because I have swum down it many times, and even though the mainline twists and turns, I know the cave well enough to know the exact direction of exit in that section, and I have a safety protocol to implement that knowledge.
A visiting cave diver making the same mistake would likely swim down the jump line away from his exit, at least until he hit a landmark indicating that he was going the wrong way. Even then, his safety would depend upon his noticing that landmark or reference point, and then having the humility to admit he made a mistake and turn around before it was too late. If he continued to fuss with his camera, he would have no chance.
Cameras Killed Cave Divers
Even when working with weaker lights, using a camera in a flooded cave is extremely distracting in an environment where one cannot afford to be distracted. Most, if not all, of the modern cave diving accidents in Mexico involve cameras and navigational mistakes as a contributing factor.
The famous Kalimba accident over ten years ago saw four divers follow an arrow away from their exit toward Grand Cenote, which they could not reach. Two of the divers had cameras. In the same cave, a more recent accident involved two divers with a camera and stages, who over-breathed their tanks while shooting, and then similarly followed arrows away from their point of entry and stages towards Grand Cenote.
A cavern diving incident in Calavera a few years back involved tourists with GoPros who swam off the line. Two years ago, in Grand Cenote once again, an instructor shot photos of a recently certified cave diver on the Cuzen Nah loop before they were separated, and one of them perished.
What’s going on? I think the caves in Mexico are so spectacularly beautiful that any photographer or videographer with functioning eyeballs will find themselves inspired to document the beauty of the cenotes. Add to this the improvements in modern photography gear (you don’t need to be a professional photographer to get good cave images) and the dopamine rush of receiving hundreds of “likes” on Instagram—which only reinforces someone’s ego and sense of identity as a badass cave diver—and it’s clear why cave photography is becoming more and more popular.
Yet many of these people are only visiting our caves and do not have the experience in cave diving, the familiarity with Mexican cave navigation, or the understanding of their particular shooting site to safely take photos in the caves. Taking photos when new to the environment has certainly proven to be a recipe for disaster. In many cases, not only do the divers capture fabulous images, they helpfully document their own demise for the accident analysis team. Do not underestimate Mexico’s shallow, warm caves.
Is Safe Cave Photography Possible?
It certainly is! The main issues with cameras and cave diving are distraction and navigational errors. There are ways to avoid this, but no quick fixes. Here are four suggestions for safe cave photography:
- If you are new to an area, hire a local guide or dive with another diver who is experienced in local protocols for at least a few days. If you are diving in Mexico, get a feel for Mexican cave diving and the complexity of the navigation before ever bringing a camera into the cave.
- Do not attempt to photograph caves you have never visited before. Scout a potential photography site first. Become familiar enough with the lines that you will be able to recognize if you get turned around. This means that you should dive past any potential scenes you plan to photograph, so that you will recognize the cave if you go the wrong direction. Even better, familiarize yourself with a cave first; it will allow you to plan a shoot which will get you better results in the end.
- Bring a diver along who is not involved in the shoot. This diver’s job is to stay out of the way and run safety. They can help to carry lights and gear into the cave, but once the shoot starts, their job is to observe the model(s) and photographer, ensuring that they do not become disoriented, that they mind their gas limits, and that they do not unknowingly impact or damage the cave. Local guides make great safety divers, as they are more familiar with the caves than visitors and less emotionally involved in the shoot.
- Always have navigational references in place when shooting. Place an arrow on the line as a mark for your model, but also to reconfirm the direction of exit when the shoot is done. Know the compass heading of your exit, and reconfirm this heading before beginning your swim out.
Where Art Thou Accident Analysis?
Why don’t we hear more about cameras killing divers? How is this not taught in basic cave courses? Perhaps it’s because no one talks about their mistakes anymore. When was the last time a formal accident report was released to the cave diving public? In our modern, politically charged and lawsuit-oriented society, stating that a cave diver made a mistake resulting in his death seems to be akin to saying the person deserved to die.
The only way cave diving became reasonably safe in the first place was through accident analysis—cave divers observed how others died and then decided, well, guess I won’t do that. These days, not only does cave diving lack accident analysis, it lacks incident analysis, the review of non-fatal mistakes. How valuable would it be if cave divers, experienced and novice alike, publicly announced their mistakes to the world? If you read that it’s important to check all your gear before every dive, it sounds like a reasonable idea, so you might do it. However, if your wreck diving hero admits he got complacent and ended up with a total light failure because his back-up lights had low batteries and he didn’t check them, it has a different and more powerful effect.
Having observed my own mistakes while filming and shooting, as an experienced cave diver with over 5,000 cave dives, I can say that what keeps me safe is vigilance and a strict adherence to safety protocols. In short, doing everything right except for my one small mistake has been what’s saved me. I have lived to tell my tales, but I will be the first to admit I am not infallible. I have missed a T intersection, swam onto a jump line while filming, and knowingly swum into an unstable cave.
Understanding that real divers, even ones more experienced than you, can and do make silly mistakes serves as a valuable reminder that no diver is infallible. This improves diver safety by keeping us vigilant against complacency and the normalization of deviant behavior. Yet, these days, it’s almost professional suicide to admit one’s mistakes so that others will learn from them, and as a community cave diving is weaker for it. Instead of ridiculing mistakes, we should thank those who admit their errors and endeavor to learn from the mistakes of others.
How many cave diving accident reports have you read recently? I don’t mean message board rumors or third-person synopsis, I mean the original, impartial report? Have cave training agencies actually run the statistics recently and analyzed incidents in the light of modern cave diving, with the advent of all the modern technology most divers use in the cave? I think perhaps that information is going missing somewhere, and one piece of that information is the prevalence of cameras in cave diving accidents.
I have been pretty vocal about what I consider the sixth rule of accident analysis which in my opinion should join the other classical five rules taught in cave diving courses. Cameras are frequently a contributing factor in cave diving fatalities, distracting divers from navigation, gas management, and a host of other safety concerns that they would normally adhere to, and I think it’s time that we talked about it.
Famed explorer Sheck Exley’s original work on cave diving accident analysis, “Basic Cave Diving: A Blueprint for Survival,” is available as free download by the National Speleological Society Cave Diving Section.
Natalie L Gibb’s passion in life is underwater cave exploration and conservation. With her exploration partner Vincent Rouquette-Cathala, she has led her team to discover over 20 previously unknown cave systems in Mexico’s Yucatan Peninsula, mapping more than 80 kilometers of cave passageways. She is a public speaker, author, photographer, and videographer, and a member of the Woman Diver’s Hall of Fame. Natalie is co-owner of Under the Jungle, a cave diver training center in Mexico, and a TDI Full Cave Instructor.
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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