The places where the Maya once suspected the entrance to the underworld are now considered Instagram hotspots by travelers. The so-called cenotes have become one of the main tourist attractions in southeastern Mexico.

The natural phenomenon is open karst caves with access to groundwater. Depending on the nature and formation, each cenote has a different look – each cave looks different. Some are dark grottos with huge stalactite formations on the ceiling. Other cenotes are open lakes surrounded by tropical plants. The word comes from the Mayan language and was originally “ts’onot”. That means something like “holy source”. No wonder, because the Maya ensured their water supply via the cenotes.

Cenotes are formed in karst areas. The dissolution of the limestone creates subterranean craters. If the ceiling collapses, the cave becomes visible to the outside world. The rising groundwater level and the rain eventually filled the depressions with water – and “transformed them into a mysterious underwater world”, as the “Tagesspiegel” describes in a report on the caves. The limestone holes average 15 meters deep, but some go as deep as 100 meters. The water in the cenotes is clear and you can often see down to the bottom.

The special caves can be divided into four categories. Cave cenotes are almost entirely closed. Usually only a small hole in the ceiling allows sunlight to shine on the water surface. Often stalactites hang from the ceiling. Part of the cave ceiling is missing in half-open cenotes. These limestone holes are often connected to other cenotes. In open cenotes, the cave ceiling has completely disappeared over the years. This is exposed but surrounded by cliffs that are often overgrown with flowers and plants. In the case of very old cenotes, the rock walls also erode over time. The water surface then lies like a lake in the landscape. Nothing remains of the original cave and rock walls.

Nowhere else in the world are there as many cenotes as in the Yucatán. The states of Quintana Roo and Yucatán are located on the 300-kilometer-long peninsula in southeastern Mexico. More than 3000 cenotes have already been discovered in the region. However, experts expect a large number of caves that are still unknown. Some estimates go as high as 10,000. Many of the cenotes are connected to a huge underwater cave system – probably the largest on earth. They form an underground labyrinth that stretches across the entire peninsula. There is also a semi-circular ring of cenotes in the north-west of the Yucatán. This particular formation formed after the impact of the Chicxulub meteorite. The aquifers follow the fractures and faults caused by the meteorite. The cenote ring thus reproduces the crater rim that was buried long ago.

For the Maya, the flooded caves played an important role in both practical and spiritual terms. The cenotes served as wells and water reservoirs for high culture in the Yucatán – where there are otherwise no larger lakes or rivers. The groundwater from the caves ensured the water supply. In Mayan belief, the cenotes were the entrance to the underworld of Xibalbá, the “Place of Fear”.

At the same time, they suspected the residence of the rain god Chac in the caves. In the Mayan worldview, the success of the harvest depended on his benevolence. In return they brought him offerings, for example during long periods of drought. Researchers keep finding altars, ceramics and bones of animals and humans in the cenotes. Such relics, which date from between 3000 BC and the ninth century, show that the Maya also sacrificed people in the caves. Some of the limestone holes probably also served as burial sites for the people. For example, the Calaveras cenote, where scientists discovered hundreds of human skeletons.

In addition, the cenotes may have also served as an architectural tool for the Maya. The locations of their famous pyramids were based on astronomical calculations. The mystical edifices, according to National Geographic, “were not just edifices. They were cosmic timekeepers in constant interaction with the heavens.” The position and construction of the pyramids are based on the rising and setting position of the sun on the equinox or the days on which the sun is exactly at its zenith. To determine the zenith, the Maya may have entered the cenotes, according to underwater archaeologists Guillermo de Anda and Arturo Montero of the Universities of Yucatán and Tepeyac. Because only on these two days of the year does the sunlight fall vertically onto the water and is not reflected on the cave ceiling.

Scientists from all over the world participate in the exploration of the cave systems. “It’s like diving into another world. As a diver and archaeologist, I don’t know of any comparable place,” quotes the “Tagesspiegel” underwater archaeologist Florian Huber. Some relics in the cenotes date back to even earlier times. Bones of prehistoric animals and objects from the Stone Age that divers have found in the groundwater are up to 10,000 years old.

At that time the caves were still dry because the water level was about 130 meters lower. The holes only filled with water when the snow and ice melted after the Ice Age. The element has preserved the relics over the long time. Sealed off from the oxygen in the air, the objects in the water have largely been spared from decay. The restoration is complex, because when it comes into contact with air, it starts to decompose immediately. The dives in the deep, winding caves are delicate missions that require a lot of preparation. The darkness and the sometimes very narrow corridors pose a challenge for underwater archaeologists. Hobby divers should never go into the cenotes alone and should not dive too deep into the narrow corridors.

Otherwise, diving in the caves is not dangerous. The caves are also very popular for snorkeling and swimming. The water in the cenotes is always at a pleasant temperature of around 24 to 25 degrees. Last but not least, the limestone holes are simply spectacular sights. Many cenotes are tourist magnets and accordingly well visited. It is advisable to visit the caves as early as possible in the day. The most popular cenotes on the Yucatán are very centrally located and are therefore easy to reach. There are also numerous limestone holes that are considered insider tips and are (still) spared from the rush of visitors. These are in more remote locations and cannot be reached without a car.

• Cenote Ik Kil

One of the most famous cenotes in the Yucatán. The cave is three kilometers south of the ruined city of Chichén Itzá. Many vacationers combine a visit to the Mayan pyramids with a subsequent bath in the cenote. A wooden staircase leads visitors 27 meters down. The deep blue water in the limestone hole is then another 40 meters deep. With the lianas dangling from the rock faces, there is a jungle atmosphere.

• Blue Cenote

The cenote lives up to its name. “Azul” means “blue” and probably indicates the numerous shades of blue in which the water shimmers. The cave is about 40 miles from Tulum and is just off the road. The open cenote is surrounded by trees and is particularly popular with families. Numerous fish swim through the clear water, so the cenote is also perfect for snorkeling.

• Cenote X’keken

Only about eight kilometers from Valladolid, the cenote can be easily reached even by bike. X’kekén is a nearly closed cave. Sunlight only penetrates through a small hole. The rock ceiling is characterized by massive stalactites, giving the cenote the appearance of an underground cathedral. Supposedly it was a pig that led people to the natural phenomenon. A legend says that a peasant family once lived near the cave. This is said to have owned a pig that kept going on discovery tours. Every time the animal returned, it was covered in mud, even in times of drought. The owners decided to follow the pig and were led to the cenote by the animal. Hence their name: “X’kekén” comes from the Mayan language and means “pig”.

• Cenote Yokdzonot

The cenote is still considered an insider tip due to its rather isolated location. The limestone hole is located 20 kilometers west of Chichén Itzá and 100 kilometers east of the metropolitan city of Mérida. Visitors can expect an open cenote with steep cliffs and green trees that grow directly above the former cave ceiling. With a bit of luck, you will have the bathing area to yourself and, unlike many other cenotes, you can enjoy nature in silence.

• Two Eyes Cenote

The “Two Eyes” are two adjacent cenotes found 20 kilometers north of Tulum. Both caves are part of the third longest underwater cave system on earth (altogether 82.4 kilometers long). The cenotes are best known for their impressive underwater limestone formations. Therefore, the flooded caves are ideal for snorkeling or grotto diving.

Sources: “The Maya. History, culture, religion”, “Deutsche Welle”, “National Geographics”, “Mineralienatlas”, “Tagesspiegel”, “Travelbook” (I), “Travelbook” (II), “Urlaubsguru”