Costumed attendees participate in the Dragon Con Parade, during the annual science fiction, pop culture and fantasy convention in Atlanta, Georgia, USA, 02 September 2023. Thousands of attendees, some costumed, crowd downtown Atlanta for the annual Labor Day Weekend gathering. (Photo by Erik S. Lesser/EPA/EFE)

An animal enthusiast touches a Bearded Dragon displayed for sale as exotic pet at Thailand Reptile and Exotic Expo in Bangkok, Thailand, 02 August 2024. The Thailand Reptile and Exotic Expo is a trade showcase exhibiting hundreds of reptiles and exotic animals from breeders to sell as exotic pets for enthusiasts. (Photo by Rungroj Yongrit/EPA)

A visitor poses next to Chinese charms and ornaments that are seen on display for sale at a shop in the Chinatown district of Manila on February 7, 2024, ahead of the Lunar New Year of the Dragon which falls on February 10. (Photo by Ted Aljibe/AFP Photo)

National Geographic has created “Air, Land & Sea: the 50 greatest wildlife photographs” exhibition. Here: CT4 Crocodile cave on the Salamat river. Set up with Nathan Williamson last chip rain came while we were with the nomads. (Photo by Michael Nichols/National Geographic)

Asia Sawicka as Anastasia IV poses for a photograph prior to a rehearsal of the Circus of Horrors' latest show Voodoo, ahead of Halloween, at the Wookey Hole Caves Theatre near Wells on October 19, 2017 in Somerset, England. (Photo by Matt Cardy/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.

People in traditional Chinese costumes attend a parade to celebrate the upcoming Year of the Dragon on January 28, 2024 in Nanjing, Jiangsu Province of China. The Spring Festival, or the Chinese Lunar New Year, falls on February 10 this year. (Photo by Yang Bo/China News Service/VCG via Getty Images)

People walk through Manhattan in a snow storm on December 16, 2020 in New York City. New York City is expected to get between 10 inches and a foot of snow on Wednesday and Thursday in what is the first winter storm of the year. (Photo by Spencer Platt/Getty Images)