A person participates in the parade of the “San Jose Carnival” in San Jose, Costa Rica, 27 December 2018. The festival sees people parading through the city's main avenues as part of the San Jose Celebrations that take place at the end of each year. (Photo by Jeffrey Arguedas/EPA/EFE)

A child is seen during celebrations of Reindeer Breeder Day, the main holiday of indigenous peoples of the Russian Extreme North, in the village of Nosok on Taymyr Peninsula in north-central Siberia, Krasnoyarsk Territory, Russia on April 17, 2021. (Photo by Alexander Ryumin/TASS)

A man wearing a protective face mask walks past traditional large puppet figures called “Ondel-ondel”, also donning face masks and displayed along a sidewalk of a main road, as coronavirus disease (COVID-19) cases surge in Jakarta, Indonesia, June 30, 2021. (Photo by Willy Kurniawan/Reuters)

Members of the Pontifical Swiss Guard stand by at St. Peter's Square before Pope Francis delivers his traditional Christmas Day Urbi et Orbi speech to the city and the world from the main balcony of St. Peter's Basilica at the Vatican, December 25, 2021. (Photo by Yara Nardi/Reuters)

A girl walks past destroyed houses at Basara refugee camp in Sittwe on May 16, 2023, after cyclone Mocha made a landfall. The death toll in cyclone-hit Myanmar's Rakhine state rose to at least 41 on May 16, 2023, local leaders told AFP. (Photo by Sai Aung Main/AFP Photo)

Tom Lishness of Windsor, who has been competing in the event since 2005, gets into position for the Damariscotta Pumpkinfest & Regatta on Monday morning, Oct. 14, 2024, in Damariscotta, Maine. (Photo by Derek Davis/Portland Press Herald via AP Photo)

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.

Elephants spray tourists with water in celebration of the Songkran water festival in Thailand's Ayutthaya province, about 80 km (50 miles) north of Bangkok, April 9, 2014. (Photo by Rungroj Yongrit/EFE)