Cambodia's Pov Sokha and Soeur Chanleakhena compete in the female pair sword form category of the vovinam event during the 31st Southeast Asian Games (SEA Games) in Hanoi on May 19, 2022. (Photo by Nhac Nguyen/AFP Photo)

Thailand's Patsapong Amsam-ang waits under an umbrella during a break due to heavy rains in the men's pole vault final during the 32nd Southeast Asian Games (SEA Games) in Phnom Penh on May 8, 2023. (Photo by Mohd Rasfan/AFP Photo)

New York Yankees' Domingo Germán, center, is doused by teammates after he pitched a perfect game against the Oakland Athletics in a baseball game in Oakland, Calif., Wednesday, June 28, 2023. The Yankees won 11-0. (Photo by Godofredo A. Vásquez/AP Photo)

Thailand's Lac Somruedee Pruepruk balances the ball during the sepak takraw women's match against Malaysia at the 31st Southeast Asian Games (SEA Games) in Hanoi on May 17, 2022. (Photo by Ye Aung Thu/AFP Photo)

A guard follows participants down a hallway in “Squid Game: The Trials”, an in-person interactive competition experience based on the Netflix show “Squid Games”, on December 20, 2023 in Los Angeles, California. At “Squid Game: The Trials” in Los Angeles, fans of all ages can relive the most emotional moments of Netflix's South Korean hit show – but there is a lot less blood and no one wins any prize money. (Photo by Robyn Beck/AFP Photo)

Joshua Patino stands on a ladder to put finishing touches on a giant dinosaur exhibit at PAX East in the Boston Convention and Expo Center, Thursday, April 21, 2016, in Boston. PAX East, an annual celebration of gaming culture, is expected to draw tens of thousands of visitors Friday through Sunday. It's a place where serious gamers can preview unreleased video games and devices, compete in tournaments, hear live music and meet others for whom gaming is a way of life. (Photo by Elise Amendola/AP Photo)

Models promote the game “Diamond Dogs” during the Gamescom 2015 fair in Cologne, Germany August 5, 2015. Hundreds of thousands of visitors will enjoy one of the world's largest computer and video game events until Sunday. (Photo by Kai Pfaffenbach/Reuters)

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.