A climate campaigner in Dublin on November 9, 2024 dresses as Lady Justice to demand that world leaders commit to a fast, fair and funded phase-out of all fossil fuels when they gather in Azerbaijan on Monday for the Cop29 climate conference. (Photo by Stedman Photography)

Madison Chock, top, and Evan Bates, bottom, perform during the ice dance rhythm dance competition at the U.S. figure skating championships Friday, January 24, 2025, in Wichita, Kan. (Photo by Travis Heying/AP Photo)

This photograph shows the famous Lyonnais fresco by CiteCreation with a tag depicting the Abbe Pierre with the word “rapist” next to it, in Lyon central-eastern France, on September 30, 2024. (Photo by Jeff Pachoud/AFP Photo)

A Nihang or Sikh warrior performs “Gatka”, an ancient form of Sikh martial arts, during a religious procession on the eve of the birth anniversary of the ninth Sikh Guru Tegh Bahadur outside the Golden Temple in Amritsar on April 17, 2025. (Photo by Narinder Nanu/AFP Photo)

This hazel dormouse is being given a once-over by a disease risk team at ZSL London Zoo, UK in May 2025, as part of reintroduction programme. (Photo by David Levene/The Guardian)

Men eat oranges from a push cart along a road as a vehicle travels past them in Karachi January 22, 2015. (Photo by Akhtar Soomro/Reuters)

People take pictures of the sunset in Berlin October 27, 2014. (Photo by Hannibal Hanschke/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.