Diving a cenote Mexico.


Let me first make perfectly clear, like Richard Nixon used to say, what a cenote is. The origin of the word is Mayan, tsono’ot, signifying a large karst hole generated by a voluminous accumulation of fresh water in underground caves, whose ceilings eventually collapsed and created the openings. There are far over a thousand cenotes in Mexico, the most renowned ones located on the Yucatan Peninsula, with depths of 15 to 100 meters. Many of them will be found in dense jungle, where quite a few have probably still evaded the eyes of explorers to this very day.


Diving Mexico’s cenotes is considered the ultimate kick for aficionados of the underwater world. The drink is crystal clear, and the fresh water accounts for huge masses of vegetation garnishing the entrances. Also, odd endemic fauna, including sightless fishes, inhabit the black depths of the caves. Just the right thing for adventure-seeking divers, then. Small wonder the cenotes rank very high on their global list of potential excitement. In fact, numerous frogmen and women from all over the world line up for the privilege of going underground in Yucatan’s jungles. And sometimes, a little crowd of explorers assembles many feet under the surface, most of them just in bikinis and swimming trunks — occasionally even less — because the water is pleasantly warm.

Sounds good, so far. But cenotes are not just oversized bathtubs to have fun in. The cave system of Yucatan extends over enormous distances. The two longest hollows, Ox Bel Ha and Sac Actun, measure 256.6 km and 222.7 km, respectively, and those of neighboring Quintana Roo, 1,085 km. All in all, this subterranean aquifer is considered the world’s largest.

The semicircular shape of Yucatan’s line of cenotes is the ancient residue of a crater ring tossed up by the Chicxulub Meteorite, which crashed to earth in these environs 66 million years ago. The asteroid probably measured 10-15 km in diameter and created a hole 10 km deep and 180 km across after hitting the ground at 50,000 mph and releasing the kinetic energy of several million atomic bombs. It was one of the greatest natural calamities ever to befall our planet, resulting in the extinction of the dinosaurs and many other species of life. The site has been reliably established by painstakingly exact surveys; and the origin of the cenotes, consequently as well. They are alien footprints, which add to their fascination, but makes them doubly sinister, too.

Incidentally, if you fear, like many other humans, that an asteroid of Chicxulub proportions might fall on your head one of these days, lean back and relax. Chances of such taking place are only once in a hundred million years.


It is easy to imagine the likelihood of getting lost in an enormous labyrinth of this size. The death of a diver under these circumstances is especially grim because without an opening to the surface he or she will just run out of air and suffocate gruesomely. And there is no need to penetrate far into the caves for this tragic event to occur. Losing one’s way just a few meters down and relatively close to the entry point can happen to the untrained daredevil at any time, mainly when carelessly stirred-up silt obscures the vision to zero, and up and down melt into one. A strong lamp, normally a necessity, is of little help in this situation, because the dust only reflects the light like dense fog. The diver, desperate to reach an exit point, swims ahead into the muck — and into his doom. There is no chance that the sediment curtain will lift before the air supply quits. As a rule it persists for several days till the water turns clear again. Silt means death, and there is plenty of it just lying in wait. Another problem zone is where freshwater lenses lie on top of saltwater, resulting in strangely blurred layers that badly reduce visibility, such as when oil is poured on water. Some divers may react confused when straying into those places, and possibly lose control in the process. Yet another obstacle is claustrophobia. Anyone tending to panic in confined spaces should refrain from entering caves, even on dry land.


Divers with caving experience are not exempt from such problems. They are rather well advised to avail themselves of the services of a local guide. Operators of some cenotes make such an accompaniment obligatory, for a fee of course. A few of them even charge for the use of a camera — greed is universal. But the most competent guide is no guarantee against accidents. Only recently a young couple, about to be married in exotic Mexico, plus their local guide, met death when they lost their way. Leading lines or “Threads of Ariadne” (so-called after Greek mythology) and markers to follow, plus strongly worded warning signs at strategic points, are meant to obviate such tragedies, but they have occurred, again and again. Rednecks poking their noses into dark abysses have regularly lost their lives, sometimes laughably close to the entrances. People in the know therefore do not cease admonishing such thoughtless characters to stick to areas flooded by daylight and to never ever let go of the lifelines when penetrating deeper into the system. The author hopes that readers of this piece will take heed of such warnings — and stay alive. 


How to get there, to that legendary land whose caves were still almost dry and accessible to Stone-Age dwellers before they flooded over a span of thousands of years? There are flights from Manila (mostly via the Los Angeles hub) to Mexico City, and thence by domestic carriers to the Yucatan. Costs a trifle, natch, but Mr. Trump will let you pass, don’t worry.