A reveler playfully sticks out her tongue during a street pre-carnival party by the “Cordao do Boitata” Block, in Rio de Janeiro, Brazil, Sunday, February 12, 2023. Revelers are taking to the streets for the open-air block parties, leading up to Carnival's official Feb. 17th opening. (Photo by Bruna Prado/AP Photo)

Brazilian singer Anitta performs during the “Ensaios de Anitta” show, an event that is part of a pre-carnival tour that makes its way through several Brazilian cities, paying tribute to a samba school in each performance at the Jockey Club of Rio de Janeiro, Brazil, 21 January 2024. Anitta only performs this time of year in her country and said that experiencing a carnival is the best way to get to know the Brazilian people because all the energy of its people is concentrated on a single topic. (Photo by Andre Coelho/EPA/EFE)

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 tourist splashes water on the frozen Songhua River on December 18, 2023 in Harbin, Heilongjiang Province of China. The water immediately freezes into ice in the frigid air. (Photo by VCG/VCG via Getty Images)

A bucket of water is splashed on a woman during the Songkran water festival to celebrate the Thai New Year, in Prachinburi Province, Thailand, April 13, 2024. (Photo by Wason Wanichakorn/AP Photo)

In this July 25, 2015 photo, youth eat a cooked pig's head as they wait for the start of carnival in Santiago, Cuba. (Photo by Ramon Espinosa/AP Photo)

A harlequin inflatable doll, part of decorations for the upcoming carnival celebrations, lays in a plaza in Caracas, Venezuela, Tuesday, February 22, 2022. (Photo by Ariana Cubillos/AP Photo)

People participate in the Cordao do Boitata carnival celebration in the Centro City neighborhood on February 16, 2020 in Rio de Janeiro, Brazil. (Photo by Bruna Prado/Getty Images)