Cenote. The Yucatán peninsula was originally under the ocean and the region’s limestone foundation is fossilized coral beds and ocean floor. There are no above ground rivers in this area. All of the ground water sinks through the porous limestone and travels to the sea in underground rivers. Parts of the limestone weakened over time and collapsed, leaving sinkholes filled with water - a cenote.
The Maya used the cenotes for water - both for drinking and irrigation - and in religious ceremonies. Some of their cities were built around cenotes or wells dug down to the ground water. Divers have explored the cenote at Chichén Itzá and have found offerings the ancient Maya made to the gods. Among them copper and gold necklaces, pottery, jade beads, and skeletons of both sexes and all ages. Today at least 1000 cenotes have been located among the approximately four thousand that are believed to exist in the Yucatán.