The Yucatan Peninsula covers an area of 300,000 km2, which separates the Caribbean Sea from the Gulf of Mexico and its topography is almost flat, with altitudes that barely exceed 30 meters and the soil is composed mainly of limestone rock, or saskab known as “white earth”. This type of rock is characterized by its high permeability. The distinctive topography of the peninsula are the cenotes and caves that are mostly concentrated in the northern part and decrease towards the south.
The word cenote comes from the Mayan word ts’ono’ot or d’zonot, which means “cavern with water deposit“, this term has become widespread to designate most of the karst manifestations in the Yucatan Peninsula. The karst has its origin in the coral reefs and marine sediments that, when exposed to the surface, formed the limestone rock, the solubilization-precipitation of this rock have promoted the absence of surface water currents that have allowed the upwelling and presence of cenotes. Likewise, the different degrees of porosity and hardness of the rock have allowed the formation from small hollows and accumulations of soil, to complex dry and wet cave systems.
The origin of the cenotes is due to the geomorphological process called karst, which consists of the combination of the mechanisms of dissolution, collapse and construction of limestone. Cenotes are complex aquatic systems generated by dissolving carbonates and other minerals from the soil, some cenotes have connections to underground currents that favor the circulation of water, where fresh and salt water coexist.
The approximate number of cenotes in the peninsula has not been estimated given the dynamics existing in its formation, however, only in the state of Yucatan are estimated between 7,000 and 8,000 cenotes; to date there is no quantification of cenotes for the states of Campeche and Quintana Roo. By their morphology, cenotes are classified according to the stage of the opening process that communicates the underground aquifer with the jungle and sunlight on the surface as described in the formation process.
Due to their hydrobiogeochemical characteristics, cenotes are classified as young and old; the young or lotic connect freely with the aquifer through the tunnels of the caves, the flow of water is horizontal and the residence time of the water is short. Older or lentic cenotes present a blockage of the main connection with the aquifer, due to the collapse of the roof or walls and sedimentation, with which the exchange with groundwater is restricted and the water turnover is slower, the water accumulates dissolved organic matter, particulate, organic detritus and living organisms, present anoxic (without oxygen) and acidic waters at the bottom.
The size of the opening of the cenote determines, to some degree, how much organic matter can be introduced from the adjacent terrains of the jungle floor in rainy seasons and the production of organic matter depends, among other factors, on the presence of light. On the other hand, the pitcher-type cenotes are less exposed to sunlight, the fully exposed cenotes such as the cylindrical and watery ones present a greater amount of organic matter: alloctone and autochthonous, the latter coming from aquatic plants and algae, and influence the type of life found in them
In the northern part of the Yucatan Peninsula, more than 600 km of flooded galleries and tunnels of different levels and vertical passages have been mapped, which includes the largest flooded cave in the world of an extension of 347 kilometers, according to data from the underwater exploration group of the Great Mayan Aquifer (GAM) project and directed by Robert Schmittner, who reported that he managed to connect two of the largest flooded cave systems on Earth known as Sac Actun and Dos Ojos, this discovery surpasses all those on the planet, refer that the union of the two caverns took 10 months and that before the discovery the Ox Bel Ha System, located south of Tulum, it was the longest in the world with 270 kilometers. The researchers said that the Sac Actun system, located northeast of Tulum, had 263 kilometers and ranked second in length and when merged with Dos Ojos it becomes the largest in the world.
On a trip through the Yucatan Peninsula you can not miss knowing some of its cenotes, now with greater knowledge that it is a cenote and for the Mayans they were considered sacred places. At present they are very visited by tourists and are ideal for bathing and diving or snorkeling, since the water is crystal clear and you can visualize a great diversity of flora and fauna. Some cenotes due to their great depth and system of underground tunnels it is possible to dive with the help of qualified experts.