Cenote

A cenote ( or ; ) is a natural pit, or sinkhole, resulting when a collapse of limestone bedrock exposes groundwater. The term originated on the Yucatán Peninsula of Mexico, where the ancient Maya commonly used cenotes for water supplies, and occasionally for sacrificial offerings. The name derives from a word used by the lowland Yucatec Maya——to refer to any location with accessible groundwater.

In Mexico the Yucatán Peninsula alone has an estimated 10,000 cenotes, water-filled sinkholes naturally formed by the collapse of limestone, and located across the peninsula. Some of these cenotes are at risk from the construction of the new tourist Maya Train.

Cenotes are common geological forms in low-altitude regions, particularly on islands (such as Cefalonia, Greece), coastlines, and platforms with young post-Paleozoic limestone with little soil development. The term ''cenote'', originally applying only to the features in Yucatán, has since been applied by researchers to similar karst features in other places such as in Cuba, Australia, Europe, and the United States. Provided by Wikipedia