It is a huge reef bank located 30 km from the coast, in front of Mahahual and Xcalak. It has an elliptical shape, with about 45 kilometers long by about 18 at its widest part. On this perimeter are the highest parts of the bank, four of which form emerged sandy areas. There is also another sandy bank inside the lagoon formed by the ellipse. With an approximate area of 800 km2 of which less than 1% is on the water, the Chinchorro bank consists of 3 keys and an interior lagoon whose average depth is 5 meters. The dive sites range from 5 to 40 meters. As an integral part of the Mesoamerican Reef System, it does not present notable differences with respect to the coral reef in terms of topography and animal life. Anemones and sponges abound, of which up to 20 species have been counted. Many of the creatures it houses are nocturnal. Of the 200 species identified to date, a large part belongs to tropical fish that tend to swim in schools. The main predators are moray eels and barracudas.
The main peculiarity of Chinchorro is the abundance of wrecks at its eastern end, the windward side. In fact, the Mexican government has declared it a marine archaeological sanctuary. Their number varies according to the source consulted, between 70 and a hundred, a length that could include a German submarine and several submerged treasures. And it would not be strange since 18 ships sunk between the years 1600 and 1800 are documented, to which is added a long list that goes as far as contemporary shipwrecks. Some still show their superstructure on the surface of the water and others rest in shallow water, allowing the tank and exploration to be lengthened for more than an hour.