Germany, Business couple making love under desk. (Photo by Roman Maerzinger/Getty Images)

A grey seal basks under a rainbow on a beach on the Lincolnshire coast, England on November 21, 2017. (Photo by Sean Weekly/Caters News Agency)

A cenote is a natural phenomenon, a sinkhole in the Earth’s surface. The Yucatan Peninsula in Mexico has an estimated 7,000 cenotes because it is primarily made up of porous limestone. For millions of years, rainfall slowly ate away at the limestone and a huge system of underground caves and caverns was formed. Many filled with water from rain or from the underground water table. When the roof of a water filled cave collapses, a cenote is born. The water found in a cenote may be fresh water, salt water, or both. Structurally it may be completely open, like a lake, almost completely closed with just a small opening at the top, or somewhere in between.

A Kashmiri Muslim woman balances on a water pipe before collecting water at Dasilpora village on March 22, 2018. World Water Day is held annually on 22 March as a means of focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources. (Photo by Tauseef Mustafa/AFP Photo)

Multicolored nets are set under olive trees to collect the olives on November 27, 2013 in Castagniers, southeastern France. (Photo by Valery Hache/AFP Photo)

Vendors selling vegetables wait for customers under a flyover in the early morning in Ahmedabad, India on February 1, 2017. (Photo by Amit Dave/Reuters)

Ukrainians pour water on each other on a street in Lviv, Ukraine, 02 May 2016. The tradition of pouring water was an ancient spring ritual of cleansing on first Monday after Orthodox Easter. (Photo by Mykola Tys/EPA)

Boys play with water as they celebrate Myanmar's New Year Water Festival of Thingyan in Yangon, April 13, 2016. (Photo by Soe Zeya Tun/Reuters)