A vast peninsula
The Yucatan Peninsula is located in southeastern Mexico and northern Central America. It separates the emerald waters of the Gulf of Mexico to the north and west from the turquoise waters of the Caribbean Sea to the east. Although the Yucatán Peninsula is often thought of as simply a Mexican region, this 181,000 km² territory geographically incorporates two other countries: Belize and Guatemala. The Mexican part (141,736 km²) represents three quarters of the Yucatán Peninsula, and 7.2% of Mexican territory. It is divided into three states: Yucatán (north), Campeche (west) and Quintana Roo (east). To the south of the peninsula lie Belize and northern Guatemala (Petén). These three countries are part of the Mesoamerican region, a homogeneous biogeographical and cultural area under the influence of the Mayan civilization.
The emergence of the peninsula
The Yucatán Peninsula consists of a large limestone plateau about 600 km long and between 275 and 400 km wide. This plateau then sinks under the sea for about 100 km to the northwest. This plate of limestone rock emerged a few tens of millions of years ago, with the accumulation of carbonate sediments from shallow seas, which covered this part of the continent on several occasions during the Cenozoic era. The present shape of the peninsula dates from the end of the Pliocene period, about four million years ago. The Quintana Roo and northern Yucatán are geologically younger than the interior of the peninsula and the Campeche. Isla Mujeres, for example, the country's easternmost island, appeared barely 10,000 years ago, and coral reefs continue to form in the north and east of the peninsula.
Dream beaches
The Yucatan Peninsula is famous for its white sandy beaches and crystal clear waters, with incredible colors. The Caribbean coast (Quintana Roo) is the most touristic area of the peninsula, with cities dedicated to mass tourism, like Cancún or Playa del Carmen. It is true that the beaches of the famous Riviera Maya and the islands facing it (Isla Cozumel, Isla Mujeres, Holbox...), without forgetting the less popular Costa Maya, offer postcard landscapes (when there is not too much sargasso)! These coasts and small islands surrounded by superb coral reefs are today massively exploited by tourism. For more tranquility, the coasts of the Gulf of Mexico (Campeche and Yucatán) are wilder, with still beautiful beaches where turtles come to lay their eggs, but also lagoons, swamps and mangroves well preserved, with an abundant bird fauna.
Little relief, little water on the surface..
The Yucatán peninsula is flat. One quickly realizes it when one climbs for example on top of the pyramid of Nohoch Mul in Cobá. The few hills that appear from the rainforest are usually ancient temples still covered by vegetation! It is only in the interior, in the south-central part of Campeche, that one can meet some elevations of more than 200 or 300 meters. So we won't come here to climb! No rafting either... In spite of abundant rainfall, there are few rivers or lakes in the peninsula, especially in its northern part. The main river in the region is the Hondo River (209 km), in the south. It originates in the mountains of Guatemala and forms a natural border between Mexico and Belize. The river flows into Chetumal Bay, near the capital of Quintana Roo. This waterway facilitated the penetration of the interior from the coast, facilitating the development of the Maya civilization. To the north, the Río Champotón (57 km) crosses the state of Campeche before flowing into the Gulf of Mexico, south of the city of Campeche. It is one of the few perennial rivers in this part of the peninsula. Like the Palizada River (180 km) or the Candelaria River (400 km) which flow into the Laguna de Términos, it is navigable. From the end of the 17th century, it allowed the transport of palo de tinte, a precious wood with a dark red sap, known in French as bois de Campêche, which was used for a long time as a dye and natural colorant. Nowadays, these rivers are popular with travellers who want to escape the crowds for peaceful excursions along the water.
... but a subsoil full of water: the magic of the cenotes
Freshwater is mostly found underground! The limestone soils of the peninsula are highly porous. They absorb rainwater, which easily penetrates underground to reach a vast network of galleries, caverns, caves and underground rivers. Sometimes, freshwater is juxtaposed without mixing with a layer of saltwater, which arrives from the sea via underground faults. Some water-filled cavities appear on the surface: these are called cenotes (when a cenote is submerged in the open sea, it's called a "blue hole"). Cenotes are formed when the limestone soil above the cavity collapses due to erosion. These natural freshwater wells, which can reach depths of several dozen meters, take a variety of forms depending on the state of erosion: some have a small circular opening of just a few meters, others are much larger and cylindrical, with steep walls, while others are completely underground, accessed by a narrow tunnel from the surface... Cenotes provide access to this entire underground aquatic network, which slowly flows out to sea. This geological curiosity is found in only a few places on the planet, and the Yucatán Peninsula is the world's most densely populated region. Many of the 5,000 or so mapped cenotes remain unexplored, and satellite images indicate that the peninsula could be home to as many as 10,000! The cenotes and underground cavities are home to an entire ecosystem of fish, bats and insects, some of which are endemic.
The word cenote comes from the Mayan dz'onot (or tz'onot) meaning "cave with water". The Maya settled in the region to take advantage of the immense reserves of fresh water stored underground, and it was near the cenotes that the great Maya cities flourished. For the Maya, these chasms also had a religious function: they represented access to Xibalba, the Maya underworld. It was here that Chaac, the God of rain and benefactor of crops, lived. The Maya performed rituals around these sacred cenotes, invoking rain and good harvests. At the Xtoloc cenote in Chichén Itzá, young men and women who had the "honor" of being sacrificed were thrown into the cenote at dawn, where they were left to drown. If they were not dead by noon, they were considered divine messengers... Some cenotes are major archaeological sites. Cave paintings, millennia-old human bones and numerous offerings (jewelry, pottery, ritual artefacts such as incense burners, etc.) have been discovered.
Today, the cenotes have become veritable natural swimming pools for tourists on the go. Their cool, crystal-clear turquoise waters, surrounded by lush forests, are a feast for the senses! Kankirixché or Chelentún in the Mérida region, Xkekén near Valladolid, Ik-Kil near Chichén Itza, or Car Wash, Ponderosa, Dos Ojos or Gran Cenote in Quintana Roo, are among the most enchanting, and for fun sites without the crowds, there's plenty of choice too. Some cenotes offer subterranean diving in large submerged galleries overgrown with stalagmites and stalactites. The water, which has been filtered through limestone and tree roots, is extremely pure and the visibility excellent. However, some of the dives are real labyrinths, making guidance by certified professionals essential. At the end of 2017, Mexican divers from the Gran Acuifero Maya scientific project succeeded in connecting the two immense underwater galleries Sac Atun and Dos Ojos, near Tulum. With the discovery of this connection, these aquatic caves would constitute the world's largest known network of underwater galleries to date (347 km), eclipsing that of Ox Bel Ha (269 km) further south. More than a geological discovery (almost all the peninsula's underwater caves are known to be interconnected), this is the world's most important submerged archaeological site.
The Yucatán asteroid
In the north of the Yucatan Peninsula, countless cenotes are connected to each other in a circular arc. It is called the "ring of cenotes". The reason for this strange shape, which can only be seen from space, is the presence of a huge crater 180 kilometers in diameter, which extends half under the Yucatan mainland, and half under the Gulf of Mexico. This is the Chicxulub crater. Today completely covered by more than 1,000 meters of limestone, the Chicxulub crater was formed about 66 million years ago, following the collision of an asteroid of 10 km in diameter with the Earth, here in the north of Yucatán! The power of the impact would have released a quantity of energy equivalent to several billion times that of an atomic bomb! In addition to gigantic tidal waves, earthquakes and volcanic eruptions, a thick cloud of dust rose into the atmosphere, gradually causing a sudden drop in temperature and the cessation of photosynthesis. This meteorite is most likely responsible for the extinction of the dinosaurs and 70% of the Earth's living species at the time...
