Cenotes of the Yucat�n is a route through the Yucat�n Peninsula of Mexico. It follows a network of secondary roads through the interior of the peninsula which the Mexican government has dubbed La Ruta de los Cenotes (The Route of the Cenotes).
The underground river systems of the Yucatan flow beneath the entire peninsula. During the ice ages when the ocean levels were much lower than they are today, what was once a giant coral reef became exposed to the atmosphere and eventually became the Yucatan Peninsula. Massive cave systems were formed by gradual dissolving of the highly porous coral limestone. These caves are called "solution caves" because they were formed by the slightly acidic rainfall dissolving the alkaline limestone. Inside the caves the geological formations such as stalactites and stalagmites are a spectacular sight to see.
Many of the caverns eventually collapsed and the sea levels rose partially or completely flooding the cave systems. The water table of the entire peninsula is filled with consists of seawater at sea level and freshwater 'floating' on top at varying depth depending on the distance from the sea. For instance, Cenote Zaci inValladolid in the central Yucatan area is about 35 metres from ground level to the surface of the freshwater and probably another 30 metres below that would be the top of the saltwater layer.