Cozumel is a flat island based on limestone, result of karst topography. The highest natural point on the island is less than 15 meters above sea level. The Cenotes are deep water filled sinkholes formed by water percolating through the soft limestone soil during thousands of years. Cenotes can be explored by snorkeling, swimming or diving, in which several marine species can be appreciated. Ancient inhabitants of the island also used the large holes in the rocks for shelter, particularly to escape the heat, by digging out small caves in the ground.
- US National and State Parks