During our last vacation in Playa del Carmen, Mexico, Matthias and I got in touch with cave diving.
Until then we had the standard PADI diver training – Open Water, Advanced OW and Nitrox. For that vacation, we had planned to add the Deep and the Cavern Diver to our collection of specialties.
The Deep Diver was interesting but the usual PADI procedure – no surprises there – and maybe that’s a good thing 😉
The Cavern Diver was different, however. At the dive center (Pro Dive Mexico), we were told that PADI doesn’t have its own course plan for this specialty and that the training is conducted by other diving organisations. In our case by IANTD (International Association of Nitrox and Technical Divers).
By the way, a cavern diver only ventures as far into the cave as you can see the light from the cave entrance.
Our instructor, Alain, was fun – a very friendly and outgoing person with a contagious love of cave diving.
The course was much more demanding than anything I’ve ever done with PADI. There was a lot to keep in mind: the correct techniques to lay the line, your position to the line, to your dive buddy and to the cave, your own body position, fin techniques to avoid kicking up silt, dive time, depth and gas consumption (you don’t want to miss your turn-around-point) and most important of all – your buoyancy!
The caves in Mexico are incredibly beautiful. Crystal clear water, amazing structures – stalagtites and stalagmites in all sizes, the play of the light that shines through the water at the cave openings and several extraordinary phenomena.
The halocline is a layer under water where salt water and sweet water mix. It is very similar to an oil immersion in water. When diving through the halocline everything becomes blurred and goes out of focus. Suddenly, a diver directly in front of you will only be visible by his divelight. If you don’t see it coming the experience can be a bit disorientating. The layer itself is approximately half a meter wide and is in some cases not horizontal but vertical.
The second phenomenon I’d like to describe can be seen at a cenote called “The Pit”. It’s a bit harder to get there than to other cenotes because it’s deeper in the jungle. The road’s not great so without a proper jeep you won’t get far. We had to carry our equipment (including tanks etc) the last part of the way.
Then you’re standing in front of a hole in the ground (ca 30m in diameter). The jump down is about 7m. Once in the water we did our check ups and then went down. At a depth of 30meters, there’s a layer of hydrogen sulfate, caused by decaying trees and organic substances. Basically, it looks like fog under water. Beneath the layer, everything is pitch dark. Very impressive!
Needless to say, we’d love to continue our training to become full cave divers.