arnotify

Rob, a friend from work, had been recommending me to dive in the Yucatan area for a while, and in particular to dive a cenote. I finally got to follow his advice and dive my first cenote today, and what an experience it was.

A cenote, or d’zenot (sacred well) in Maya, is a collapsed cavern part of an underground system of caves, caverns and rivers flowing to the sea, carved over centuries by the rainwater penetrating the limestone. At the surface they appear as large sink-holes in the middle of the jungle but they are doorways to a fantastic underwater world.

I dived the cenote Chac Mool (the claw of the Jaguar), located south of Playa del Carmen.

The water in the cenotes is clear as air, offering visibility of over 70m. The Chac Mool cavern featured stalagtite and stalagmite, proof that it was dry at some point. Indeed, during the last Ice Age, some 12,000 years ago, the water level of the world’s ocean was some 100m lower.

Some of the stalagtites and stalagmites are slanted at steep angles which is another sign of the violent geologic event that shaped the region. Sixty-five million years ago an asteroid 10 to 20 km wide collided nearby at the present day location of the Chicxulub village, pushing 70% of Earth’s species, including the dinosaurs, into extinction. Some fossils were also visible, embedded in the limestone.

In contrast to the signs of these dramatic events, the shafts of light peering from the surface evoked the peacefulness of a cathedral. When crossing the halocline, the boundary between fresh and salt water, at about 10m of depth, the light is distorted at it passes through the water, enshrounding you in a dream-like haze.

It was a fantastic experience and incidentally my 100th logged dive. What a way to celebrate. Thanks Rob.

Some people really should not dive.

After your initial dive training, you get a certification card, or C-card. Mind you, unlike a driver license, once you have a C-card it never expires and cannot be revoked. Unfortunately, maybe.

This makes some sense, though: at the wheel of a car you could hurt many more people than yourself. With diving, if you do something stupid, you´re the one most likely to suffer the consequences.

This afternoon’s dive offered several examples of what not to do as a diver, from the minor to the frightful.

During the dive briefing, the divemaster is always very clear about what you´re supposed to do and not to do. This time, as always, Miguel reminded everyone to follow him and stay behind him.

All the dive sites over the Cozumel reef are drift dives. That’s the easiest and most relaxing way to dive: you just let the current carry you along. You don´t even have to kick your fins. You can just sit back and enjoy the ride, literally.

Now, if you start kicking, you´re going to go fast. You´re going to go much faster than everybody else and you will end up separated from your group. That´s what happened to four of the divers. They went way past the lead divemaster into the blue yonder. Miguel, our divemaster, started banging his tank to get their attention and gestured for them to come back and rejoin the group. Did they? No, of course not. One of them, once they were back on the boat, even complained that the divemaster was banging on his tank. Well, duh.

That was funfest number one. Now, Cozumel is a national marine park. To preserve the fragile reef ecosystem, you should not touch any sponge or coral. You could accidentally break it. But the natural oil on your skin also degrades the protective coating that protects those fragile organisms from bacteria. The divemaster also reminds you of this during the dive briefing.

But one of the divers in our group was a grabber. Accidents happen and sometimes you brush against a sponge. But this guy was just grabbing and holding on to sponges. Repeatedly. He also grabbed some of shrimp and started playing with it. Argg… Why on earth would you do that?

I must say in general that divers are quite well behaved. After all, if they want to keep enjoying diving, it is in their interest to preserve the reefs. But there always has to be an exception.

And now for another behavior that could land someone a Darwin award. It was actually a combined effort. One of them was a diver with our group (one of those that kept getting separated) and the other was a young snorkeler, a friend of the diver.

The snorkeler was tagging along with us and from time to time would freedive. At one point, as the snorkeler was freediving, the diver gave him his spare second stage and the snorkeler took a breath.

Now, and it apparently wasn´t obvious to either one of them, but this is a really bad idea. He took a breath of compressed air, then zoomed back to the surface. When you do that, the air in your lungs expand because of the difference in pressure between the depth and the surface (Boyle´s law). As a result you can end up with more air than your lungs have the capacity to hold. This can create all sort of interesting things, including arterial gas embolism (the lung´s alevoli are distended, then rupture, then gas leaks into the arterial), mediastinal/subcutaneous emphysema (the lung tears and air leaks into the cavity between the two lungs) or pneumothorax (collapsed lung).

When he saw this Miguel started gesturing big no-no signs. Once we were back on the surface he told the diver not to repeat that performance, and she was acting somewhat bothered, wondering what she had done wrong. Now, when you don’t really know what you’re doing and someone tells you “what you just did was very dangerous”, please, believe them. Don´t just argue with them and say “well, nothing happened”. The point is that something could have happened.

Each diver is responsible for their own actions. A divemaster is only there as a guide and advisor. Whether you decide to follow their recommendation or not is your call. After all, it´s your life.