In the heart of the jungle of the Riviera Maya, state of Quintana Roo, there are some special dive sites that cannot be found anywhere else in the world. Cenotes are an opening in the surface in a system of underground rivers more than a thousand years old.
The entire Yucatan Peninsula in Mexico is made up of limestone, which contains slightly water-soluble calcium and magnesium carbonates. The water infiltrated, over time, has created rivers and underground natural caves. When the roof collapses and sinks into the water, forms what we know as a Cenote.
The beauty and mystery of the Cenotes
These cenotes are connected to each other like a network of underground galleries covered with stalactites and stalagmites.
Some cenotes, near the coast, join the sea, and the encounter of fresh and salt water produces a chemical effect, called halocline. Halocline is produced because fresh and salt water have different densities and refraction causes blurring. This effect can occur at different depths, when fresh and salt water meet. You can find it in the Cenote Carwash at 21 m / 70 feet, and Naharon at 12 m / 40 ft, both in the Riviera Maya, close to Tulum. This encounter also gathers an extraordinary variety of aquatic fauna.
Another chemical effect, is knowed as hydrogen sulphide. It comes from decomposing vegetation underwater, producing a cloud of misty gas, smelling like rotten eggs. So this dense cloud produces the vision of a false and dismal bottom. You can find it in the Cenote Angelita at 30 m / 100 ft, and in the Cenote Orquidea at 21 m / 70 ft.
Even though visibility in a cenote is up to 60 meters, because there are no currents, waves, sediments or floating particles. Different chemical reactions can reduce it, and produce nausea and dizziness to the diver. On the other hand, it is important to have good buoyancy, because inside the cave there are rock formations around you.
The cenotes were sacred places for the Mayan civilization, as water sources and the door to the dark side. Here it is where the world of the living connected with the underworld, ruled by demons and evil gods. When diving into its deep and crystal clear waters, you can understand these dark Mayan connotations. You get the feeling like you’re really crossing over into the underworld.