Female Ukrainian cadets, wearing new military uniforms designed specially for women, take part in a training during the "Uniform matters" event organised to present the outfit and test it under military training conditions, on the outskirts of Kyiv on July 12, 2023. (Photo by Sergei Supinsky/AFP Photo)

A couple shelter under an umbrella during a heavy downpour of rain in Belfast, Ireland on Monday, July 31, 2023. (Photo by Liam McBurney/PA Images via Getty Images)

The Milky Way rising above Durdle Door in Dorset, United Kingdom on Saturday night, March 18, 2023. The image consists of 19 two-minute exposures, ten of the foreground and nine of the sky which needed a motorised star tracker to ensure the Milky Way wasn't blurry. All the photos were merged together to reveal more detail than what the naked eye can see. (Photo by Nick Bull/Picture Exclusive)

Russian model Irina Shayk in the last decade of August 2023 sent fans wild with these shots of her posing topless on rocks. (Photo by irinashayk/Instagram)

Japanese artist Sachi shows off her creation of a realistic 3D cat portrait, made by using felted wool, at her house in Sagamihara, Japan, January 21, 2022. (Photo by Akira Tomoshige/Reuters)

Actors, clowns and mime artists celebrate “Humor Day” in St Petersburg on April 1, 2022. April 1 is also referred to as “April Fool’s Day” and is a time for playing pranks in the country. (Photo by Anatoly Maltsev/European Press Photo Agency)

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.