Men dressed as soldiers pose with models before the opening of the Gamescom 2013 fair in Cologne,Germany, on August 23, 2013. The Gamescom convention is Europe's largest video games trade fair. (Photo by Ina Fassbender/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.

Japan's Shingo Kunieda celebrates with trophy after winning the men's wheelchair tennis final against Argentina's Gustavo Fernandez at the French Open in Paris on June 4, 2022. (Photo by Gonzalo Fuentes/Reuters)

American model Zion Moreno attends the Netflix film “White Noise” and opening ceremony red carpet at the 79th Venice International Film Festival on August 31, 2022 in Venice, Italy. (Photo by Andreas Rentz/Getty Images for Netflix)

Norway's Casper Ruud jumps in a swimming pool after winning the Barcelona Open in the final match against Greece's Stefanos Tsitsipas in Barcelona, Spain, on April 21, 2024. (Photo by Albert Gea/Reuters)

Torchbearers Charles Antoine Kouakou, Fabien Lamirault, Elodie Lorandi, Nantenin Keita and Alexis Hanquinquant gesture after lighting the Cauldron to conclude the opening ceremony of the Paris 2024 Summer Paralympic Games at Place de la Concorde on August 28, 2024 in Paris, France. (Photo by David Ramos/Getty Images)

A visitor views “Giant Pumpkin, no1” by British artist Anthea Hamilton during the Frieze Art Fair in Regents Park in London on October 12, 2022. The fair is open to the public 14–18 October. (Photo by Guy Bell/Alamy Live News)

Czech Republic's Tomas Machac in action against Norway's Casper Ruud during their men's singles match on day two of the Australian Open tennis tournament in Melbourne on January 17, 2023. (Photo by Hannah Mckay/Reuters)