National Geographic Society Newsroom

Diving the Cavern Zone – part 2

Training to Dive the Cavern Zone I was so anxious the get in the water, but I knew that I must first demonstrate proficiency in the skills necessary to pass the course and most importantly, the stay alive and enjoy this wonderful world. We decided that the best course for us was the one offered...

Training to Dive the Cavern Zone

I was so anxious the get in the water, but I knew that I must first demonstrate proficiency in the skills necessary to pass the course and most importantly, the stay alive and enjoy this wonderful world.

We decided that the best course for us was the one offered by National Association for Cave Diving Certification. Their philosophy is based on quality training, safe techniques and respect for the underwater environment. The NACD is also an advocate for diving with a partner, which is ideal for any emergency situation.  This also allows the team to know each other’s strengths, habits, and configuration.  Ideally, your dive buddy carries a perfect duplicate of your gear and in case of failure. There’s no questioning of who has what, where it may be, or most importantly, what to do!  The reaction should be identical for both.  To some extent, redundancy ensures safety and eliminates risk.    We were lucky with this since Dominique and I now have identical cavern equipment and we are taking the course together.

Our cavern course was taught by Alex Alvarez, who is a Mexican explorer and operator of Acuatic Tulum and has been diving and living in Tulum for over 20 years.  His experience in cave diving, knowledge of the cenotes in the region, and his training as a cave dive instructor for NACD, not to mention his great personality and friendship, were simply perfect for us.  The cave course takes a few days to go through and it includes classes on the NACD philosophy, knowledge of the underwater environment, types of formations, and overall history of their evolution.  The techniques specific for cavern exploration are taught and tested through field exercises.  Once you got this down, you follow with open water drills and a minimum of four cavern dives where you put to work what you have learned.   That’s when you begin to wonder, why am I doing this…

Laying Down the Line

Every exploratory dive into a cenote involves laying a line.  The purpose of this line is simple: it allows you to track where you have been, sort of like setting a route for climbers, and is just as important.  So, there are procedures associated with laying the line, how you tie it off, where and when to make tie-offs, and most importantly, in case of emergency, this will be your lifeline.  Yes, you will follow it back to safety.  So as you can see, it is important how and where it is placed.  Now, imagine running out of air or some type of failure that limits your air and you are 20 meters (60 feet) down, and 60 meters (200 feet) away from the entrance of the cenote and under an overhead environment, with very limited light.  Let’s make it even more spicy: imagine you panic for a second and your fins kick up silt that had been sitting on the bottom of the cenote.  Now you’re in trouble, you are out of air and you can’t see a thing. What do I do?

There are countless Cenotes in the Yucatan Peninsula. Aktun Ha is one of them. Photo by Fabio Esteban Amador


First of all forget about dropping your weights or inflating your buoyancy compensator, this will only pin you on the ceiling of the cave.   Forget about ripping the regulator off your buddies face, or simply losing your cool.  What I appreciate about cavern training is that is takes your mind off of these end-of-your-life scenarios and simply tells you to react as you have been taught.  First of all, provide your buddy with your primary regulator and take your backup primary, which is nicely hanging below your chin.  Second, don’t panic. You are breathing air and this is all you need to survive.  OK, now I have to get out.  NACD training enables you to safely position yourself and the person with whom you are sharing air, to be in contact with each other, and to be on the line together.  Yes, this simple, inexpensive string now becomes your road to safety.  So, my last day with Alex we laid the line, we went towards the end of cavern zone, and then he turned towards me and used the signal for “out of air”!  Oh yeah, it’s a special feeling and I’m happy to say that it went well.  As we buddy breathed and made our way out following the line, he gave the zero visibility sign.  Oh man, then I was blind and out of air.  Something strange happened at this point in my training.  Closing my eyes became a dose of tranquility that I never expected. I was breathing fine, I had my hand on the line and I could feel my buddy’s grip.  We were ok.  Although in complete darkness, and in a precarious situation, I knew that we were going to be OK, and we made it out OK.  This training is vital to your survival.

Given our intention of exploring cenotes in order to document archaeological and paleontological sites, it was vital that our training began with the proper dive training.  The training that Alex gave us was an essential part of our initiation into this wonderful underworld.  It taught us much about the cavern environment and its safe exploration within the specified limits.  The course was also very particular in making sure that dive planning, emergency procedures, preferred propulsion techniques, and perfect buoyancy were practiced over and over and should continue to be part of every future dive.

Skills learned in the cavern certification course are practiced every dive. Photo by Henry Watkins from Fisheye Photo


Planning the Dive

Planning is critical before every dive in the cavern environment.  Different than setting objectives, it actually delineates maximum guidelines that include; A. Sequence or the order of the team.  This is essential since every member of the team has a particular task in either laying the line, providing lighting for tie-offs, checking equipment, etc.  B.  Air or determining the maximum air to be used during the dive.  Now, this brings me to a point that is an imperative to cave and cavern divers – The Rule of Thirds.  This means that your immersion into a cave will be limited by the amount of remaining air.  So you divide your air into thirds, say for example, you start your dive with 3,000 psi, then 1,000 psi would be “the third,” and the first person to consume this amount will have to call the dive.  This is one of the most important safety measures since it allows you to return to the starting point with 2/3rds of your total air.  Some deaths have occurred when divers use up most of their air on their way in and then get lost on the way back or it takes longer and they run out of air.  This risk is completely eliminated by using the rule of thirds.  C.  Depth and Duration.  These last two are also essential in the pre-dive plan and are governed by the very definitions of the “cavern zone”.  The Cavern Zone is an area where the sun is your primary source of light. Although this “light” differs from cenote to cenote, the idea is that there should always be a direct line of sight to the light that enters the underwater environment.  Once you no longer can see this light, then you have entered the cave.  Nevertheless, there have to be standard measurements to prevent accidents and therefore a maximum depth of 20 meters (60 feet) and a maximum horizontal distance of 60 meters (200 feet) from the entrance should be observed, no exceptions.  This is brilliant because it eliminates the need for decompression and multiple dives are possible in one day.  And since air consumption is intimately tied to your depth, then your max depth, distance and time are the limits to be observed.

There's nothing better than having a great instructor. Photo by Local Diver.


Any Person Can Call the Dive at any Time and for Any Reason

This phase of my training was exciting, it is on the very edge of what I have been comfortable with in my life and in diving.  In many ways is testing my capacity to be in control of myself in different situations and this is something very positive.  I say this because in extreme or dangerous situations there are reactions that could either give you a fighting chance or pull you down.  In my case, I have been fighting my own demons for a while: anxiety, fear of the unknown, diabetes, etc.  Down in the cavern I have had those demons come up and I have had moments of panic, but this training has given me a different perspective.  One that life is wonderful, and that I’m doing this because I want to live and not because I’m looking for ways to die.  I’m stronger yet humble, in terms of my capabilities and limitations, and respectful of the cenotes.  Many friends have said, that’s the most dangerous sport in the world!  Well, I could think of many other crazy sports that are dangerous, but in this situation, you are in control of the situation, and understanding this allows you to perceive the beauty that once was fear of the unknown.  I am grateful for this experience and to my buddy Dominique and my instructor Alex, who never pushed, and always believed in me. Cavern diving is not for everyone, but what I have discovered here below the surface is more liberating and enlightening than anything I have ever known.  I’m flying down there, it’s beautiful, it’s fragile, it’s amazingly complex.

Part 3 of the Cavern Diving blog will focus on cenote explorers who live in Tulum, stay tuned…

About National Geographic Society

The National Geographic Society is a global nonprofit organization that uses the power of science, exploration, education and storytelling to illuminate and protect the wonder of our world. Since 1888, National Geographic has pushed the boundaries of exploration, investing in bold people and transformative ideas, providing more than 14,000 grants for work across all seven continents, reaching 3 million students each year through education offerings, and engaging audiences around the globe through signature experiences, stories and content. To learn more, visit or follow us on Instagram, Twitter and Facebook.

Meet the Author

Fabio Esteban Amador
Fabio Esteban Amador is an archaeologist, science communicator and visual artist. He uses visualization tools to get people excited about seeing, understanding and preserving their world and history. He is currently using gigapan technology, underwater imaging systems and aerial photography and video to capture art and culture around the world. Lately he has focused in the development of a new concept, strategy and workshop called the Art of Communicating Science, aimed at using creativity and visual technologies in exploration, discovery and story telling. He started his career as an art student at the School of Visual Arts in NYC and followed his interests in becoming an expedition artist by graduating as an archaeologist from the State University of New York at Buffalo. Lately, he has focused on the archaeology and exploration of caverns in Quintana Roo, Mexico, photo-mosaicking shipwrecks in Latin America and the Caribbean and capturing images and video from aerial platforms to document archaeological sites to create digital elevation models. Amador’s continued effort in communicating science has allowed him to use photography, cinematography and other multi-media tools to reach large audiences through his public lectures at universities, presentations at international scientific and professional symposia, publications in scholarly journals and on National Geographic’s Explorers Journal and NatGeo News Watch online blogs. Currently, he is a senior program officer for the National Geographic Society / Waitt Grants Program, promoting and coordinating scientific and exploratory research around the world. He is also an associate research professor at George Washington University and Executive Director and President of Fundacion OLAS, an organization devoted to capacity building for Latin American scholars dedicated to the study and preservation of the submerged cultural heritage.