A performer entertains the crowd during a rally in support of the leader of the Cameroonian opposition party Movement for the Rebirth of Cameroon (MRC) in Yaounde, on September 30, 2018, prior to the upcoming October 7, presidential elections. (Photo by Marco Longari/AFP Photo)

Moldova's Victor Ciobanu in action with Georgia's Dato Chkhartishvili during the men's 60kg semi final at the World Wrestling Olympic Games Qualifier in Sofia, Bulgaria on May 8, 2021. (Photo by Stoyan Nenov/Reuters)

Members of the Texas Dancin' Divas take part in the Juneteenth Parade in Galveston, Texas, U.S., June 19, 2021. The United States marked Juneteenth for the first time as a federal holiday commemorating the end of the legal enslavement of Black Americans. (Photo by Adrees Latif/Reuters)

This picture taken on September 2, 2023 shows a player scoring a try by jumping into Lake Geneva next to a swan from a floating rugby field during the Water Rugby Lausanne, a three-day tournament organized by the LUC Rugby that gathered more than 240 players in Lausanne, western Switzerland. (Photo by Fabrice Coffrini/AFP Photo)

Groundhog Club handler A.J. Dereume holds Punxsutawney Phil, the weather prognosticating groundhog, during the 138th celebration of Groundhog Day on Gobbler's Knob in Punxsutawney, Pa., Friday, February 2, 2024. Phil's handlers said that the groundhog has forecast an early spring. (Photo by Barry Reeger/AP Photo)

Tom Nevins guts a feral pig sow during hunting on Silver Plains Station on October 8, 2011 outside of Coen, Australia. Feral pigs are recognised as environmental and agricultural pests reported to have a population of up to 23.5 million over around half of Australia. The Cooktown Hog Hunt is held annually with this year's hunting window open from registration at 2pm on Friday to the end of weigh in at 2pm on Sunday afternoon. (Photo by Mark Kolbe/Getty Images)

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.