Chac Mool Cenote

The road in is 1.5 to 2 km of dirt off Highway 307, and some guides tell you to watch the undergrowth for jaguars on the way down it. What you park at is a gated property in the jungle with two small openings in the ground, a short walk apart, and fossil shell and coral lying loose between them. You get shown both before you kit up, and neither looks like much. One is not far off a rock pool with a stone staircase and a swimming pool ladder set into the water. The other is a flight of steps down into a small cave.

Kukulkan is the bright dive and it comes first. In through the pool at one end, and the passage opens wide and white, the limestone pale enough that a torch beam comes straight back off it with stalactites and fossils set into the walls. The route runs a big loop around the cenote with rock over roughly a fifth of it, so daylight stays in view through most of it. Somewhere around 10 or 11 m the halocline arrives. It is not a shimmer. The water goes oily, the diver in front of you smears out, and nothing resolves properly again until you sit above the layer or below it. Then you turn back towards the entrance and the reason everybody books a morning is hanging in front of you: a sheet of light coming down through the opening among tree roots and branches trailing into the water, with your own bubbles collecting and shining along the ceiling.

The second dive starts a walk away at Little Brother, down the stairs into the small cave, and everything the first dive had loosely this one has hard. Rock covers about two thirds of it and the brightness halves. This is the decorated half, stalactites at every size, columns, breakdown on the floor. The line runs past the green surface glow of Chac Mool's own opening with small fish hanging in it, then climbs into the air dome, where a section of ceiling has collapsed and the group surfaces in a room hung with tree roots and lit through a single skylight. People stand around in there with their regulators out for a few minutes. It is the part they talk about afterwards. The way back out runs downstream, and that direction carries a little more water movement than anything else on either dive.

The light here comes in sideways. Kukulkan's opening is a gap in the side of the cavern screened by roots, not a hole in a ceiling, so what falls through it is a curtain rather than a column and it needs the sun low to make it. That is why this is a morning dive in every month of the year, and why the winter sun works better than the summer one, which is the reverse of the deep sinkholes further south. Their beams are vertical and want the sun almost overhead. Same coast, same limestone, opposite half of the year, and the difference is nothing but the shape of the hole.

The two dives are then arranged as a progression, and it is legible in the water and not only on a certification card. The first is wide, white and mostly open. The second is smaller, darker, roofed for most of its length and finishes underground in a chamber you surface into. A diver who arrives having never had rock overhead does the easy version of the thing in the morning and the real version after lunch, in that order, from one car park, and comes out understanding why the two are graded apart.

Almost nothing lives here, and that is the point of the place. The interest is geological and optical: white rock, a curtain of light, a boundary between fresh water and salt that you can feel on your face, and shells and corals lying in the walls from when this limestone was a seabed. Casa Cenote up the coast is the opposite case, where the sea comes into the cave and brings animals with it. Here the cave is closed and quiet, and what you are looking at is water and stone.

The cave under the property is called Sistema Chac-Mol, and in Maya that name is a jaguar's.1 Above ground the word points somewhere else entirely. A chacmool is a reclining stone figure from pre-Columbian Mesoamerica, used as an altar for offerings, and its original name has never been recovered. The two meanings share this property and nothing else.

Divers first went in during May 1996. Gary and Kay Walten opened it, mapping started the following month, and the survey that finished the job in January 2000 measured 9,193 m of passage reaching 28.3 m below the surface across nine cenotes.2 It is neither the longest nor the deepest cave on this coast, and none of the rest of it is on the guided route, which uses the first few hundred metres from two of those nine entrances. Deep on the downstream cave line stands a stalactite called Xix Ha Tunich, the drip water stone, recorded as the largest ever measured underwater and put at around 12 m. Cave divers pass it on their way to an exit at another cenote. Nobody on a tour will see it.

In April 2012 three people died here on a guided dive, two customers and their guide, the first time recreational divers had been lost on a guided cenote dive anywhere in this region. The cenote closed for several weeks and the rules that came out of that closure are still the ones in force: the heaviest guiding credentials on this coast, and two guidelines in the water that deliberately do not meet.

Your camera stays in the car. Not a fee, a flat ban on cameras of any kind, and at the other gates along this coast an extra 200 to 1,000 pesos buys a camera in while here no amount of money does. The stated reason is protection of the cave. A professional photographer works the site instead and sells his pictures at the end of the day for something between 25 and 60 US dollars a head, in cash.

The rule that matters underwater is the line, and the clearest version of it comes from a working local guide: stay within arm's reach, and if your guide leaves the line and starts leading you off it, stay on the line, call the guide back to it, and say so at the gate afterwards. That is not theory here. The permanent cavern line and the cave line beyond it are deliberately left unjoined, about 20 m of bare rock between the end of one and the start of the other, precisely so that a tour cannot drift from one onto the other. Crossing the gap needs a jump line, a full cave skill that cavern divers are neither trained nor permitted to use.3

Book the first slot of the day. The curtain is a morning thing, no cenote dive on this coast may begin after 15:00, and the standard product is an 08:00 to 08:15 pickup in Playa del Carmen, two tanks either side of lunch on the surface, back by mid afternoon. Get in the water somewhere in the week before you come, too. The card the gate asks for is Open Water, but buoyancy is what this dive actually costs you, and guides here will ask how many dives you have and how recently you did one. Expect to be watched in the open water before anyone takes you under rock.

Bring pesos. The gate takes 250 to 300 in cash and it is charged against the property, so one payment covers both entrances and both dives. Whether your operator has already included it is the biggest single reason quotes for this day range from about 3,000 to 3,800 pesos, or 150 to 240 US dollars. And nobody sells snorkelling here, so a companion who is not diving has the restaurant and the drive back, which makes this the wrong cenote for half a group.