A boy and a serviceman pose for a picture during Marines Day celebration in the Black Sea port of Sevastopol, Crimea, November 27, 2016. (Photo by Pavel Rebrov/Reuters)

American singer-songwriter Katy Perry in the second decade of June 2024 posed in a white bra top with heavy black metallic leg armour to announce her new single Woman’s World. (Photo by Katy Perry/Instagram)

Scarlett Johansson, Florence Pug, Rachel Weisz and David Harbour star in the action spy thriller “Black Widow”. Pictured: English actress Florence Pugh as Yelena. (Photo by Splash News and Pictures)

A black gibbon is seen in a cage before being released into the wild by Indonesian nature conservation agency (BKSDA) in Jantho forest, Aceh province on August 26, 2021. (Photo by Chaideer Mahyuddin/AFP Photo)

Climate change activists dressed up as black birds protest in St. Ives, on the sidelines of the G7 summit in Cornwall, Britain, June 11, 2021. (Photo by Dylan Martinez/Reuters)

A black bear cub performs for its mum at the Pocosin Lakes National Wildlife park in North Carolina, US in January 2022. (Photo by Jennifer Hadley/Animal News Agency)

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)