A cenote is defined as a natural well that is the result of the collapse of the limestone bed that exposes the groundwater below. They are especially associated with the Yucatan peninsula of Mexico, the cenotes were sometimes used by the ancient Mayans to offer sacrifices in them. The term has also been used to describe similar karst features in other countries such as Cuba and Australia, and its more generic term is sink.
What is cenote
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These are deep well formations, which are fed by filtered rain and connections to underground river currents. The Cenote Azul, for example, is a favorite of the Riviera Maya and the Cancun cenotes attract many tourists. These wells attract divers who have documented extensive flooded cave systems, some of which have been explored to lengths of 340 km or more.
Most of these wells are protected sites and do not necessarily have water exposed to the surface. Only in Mexico there are more than 6,000 Yucatan cenotes, and the abundance of these is thanks to the calcareous soil in the peninsula, since thanks to the presence of calcium carbonate, the water from the rains is stored in the soils, forming these deposits.
The term is derived from a word used by the Yucatecan lowland Maya tz'onot, dzonot or Ts'ono'ot to refer to a cavern with water. These are common geological forms in low latitude regions, particularly on islands, coasts and platforms with young post-Paleozoic limestones that have little soil development.
History of the cenotes
Its origin dates back to about 65 million years, when the meteorite that caused the extinction of the dinosaurs in the north of the Yucatan peninsula produced with its impact the creation of sinkholes that later, during the Pleistocene, would form the cenotes as seen know today.
These were very important for the Mayan culture, for whom these natural paradises represented a key element of their rituals. For this reason, many cities of this civilization had settlements in their vicinity. That is why endless beliefs and myths revolve around them, preserved until today.
For them, the underground caves of these vaults represented entrances to the world of the dead or the Xibalbá. Numerous rituals were performed there, including human sacrifices, especially of children under 11 and men, although it is believed that virgin women were also sacrificed. The Mayan temples were located next to these cenotes so that their sacrifices were rewarded with water.
Cenotes characteristics
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The origins of its formation date from the Pleistocene, when sea levels fell during the ice ages, exposing the coral barrier. This was eroded by the rains that combined with carbon dioxide from the atmosphere, causing swamps, tunnels and underground rivers to form, to later form cenotes.
The dissolution of the rock and the resulting void may or may not be linked to an active cave system and subsequent structural collapse. Rock that falls into the water is slowly removed by dissolution, creating room for more collapsing blocks. The rate of collapse increases during periods when the water table is below the ceiling of the void, as the ceiling of the rock no longer rests on water.
Its shape is circular, forming a dome that keeps it covered in principle, but as time goes by, the body of water is exposed by the collapse of the dome. In them formations such as stalactites can be created, which are molded due to the fall and dripping of water through the limestone rock.
Fauna
In them you can find freshwater and saltwater animals, which have arrived there through the underground channels that connect them and the sea (among them are mojarras and snappers). The most abundant are the catfish and the gruppy, of which it is believed that they arrived there transported by hurricanes. You can also find crustaceans, shrimp, sponges, mud eel, blind white lady and blind eel (these very present in the depths of aquatic caves), among others.
It is not unusual to observe animals such as turtles, butterflies, swallows, Toh birds, frogs and other reptiles in their vicinity. Thanks to the discovery of fossils, it was possible to have evidence of the presence of sharks and sea cows.
Flora
In them you can find different types of flora according to their location and how close they are to the sea. Accordingly, the landscapes of those that are closer to the coast or further away are full of coconut palms, cocoa trees, guaya trees, chicozapote trees, ceiba trees, among others. Climbing plants, ferns and various mosses can be found on the walls of the caves.
Phytoplankton, microalgae, and other vegetation can be found in water that oxygenate the waters and harness the Sun's energy for other organisms that cannot synthesize their own supplies. You can also find species that float such as duckweed, water hyacinths, water cabbages and sun flowers.
Waters
It is often very clear as it comes from rainwater slowly seeping through the ground and therefore contains very little suspended particulate matter. The flow of groundwater within a cenote can be very slow. Its coloration will depend on the production of its microorganisms, and may be oligotrophic conditions, which present transparent waters and little production (such as the Crystalline Cenote of the Riviera Maya); eutrophic, whose color is green and have a high amount of food; and dystrophic, whose color is brown, since they present dissolved particles.
The temperature of its waters does not exceed 24ºC, they do not present waves, they present a great depth and may have little on their shores. They are usually fresh water, and may have the presence of salt water to the extent of its proximity to the sea, presenting a phenomenon known as halocline.
Types of cenotes
- Open cenotes: they are characterized by being similar to lagoons, since they are not surrounded by any type of wall, but by multiple trees. This is due to the previous total collapse of its upper structure, as in the case of the Cenote Azul, which is open with walls that do not surround the body of water. Sometimes they can have small islets.
- Semi-open cenotes: these are the ones that are almost completely covered, but have an entrance on the roof of their dome. To access them, you must go down an underground path until you reach the dome that contains the water. In these you can see stalactites and bats. An example would be the Cenote Ik Kil.
- Underground cenotes: these are submerged and below the surface of the earth, being that these are mostly caverns. They are the youngest type of cenote, since they have not finished succumbing to erosion and their dome has not finished collapsing. An example of this is the Cenote Dos Ojos.
Pollution of the cenotes
In some of these natural wells, contamination has been evidenced due to unscrupulous people dumping garbage into them. Likewise, the lack of basic public services in populations where these are found, such as sewage and drainage services, these discharge into some of these cenotes, which is why fecal material has been presented in some of them.
Cenotes of Mexico
- Cenote Ik Kil (near the ruins of Chichén Itzá in Yucatán). It is an open-air one, where you have access to various activities, such as bicycle rental, various shops, restaurants, and lodging places.
- Cenotes in Mérida, such as Noh Mozón, which is an open one that not many tourists dare to approach due to its remote location; the Homún cenotes, which can be visited freely or by motorcycle taxi.
- Cenotes Tulum, among which are the Gran Cenote.
- Cenotes Cancun, among which are the Chikin-Ha, where you can dive and is 22 minutes from Playa del Carmen, which can be accessed by taxi or bus.
