Sumo wrestlers in their women's match at the 2021 Russian Sumo Championship at Ak Bars Wrestling Palace in Kazan, Russia on February 14, 2021. There are over 6,000 sumo wrestlers in Russia. (Photo by Yegor Aleyev/TASS)

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.

Russia's Maria Sharapova carries the torch during the opening ceremony of the 2014 Winter Olympics in Sochi, Russia, Friday, February 7, 2014. (Photo by Matt Dunham/Associated Press)

The Rossiya (Russia) brig sails along the Neva River during a dress rehearsal of the 2021 Scarlet Sails Festival for school leavers in St Petersburg, Russia on June 25, 2021. (Photo by Peter Kovalev/TASS)

March 11, 2008 Swiss car manufacturer Rinspeed made quite the splash at the Geneva Motor Show with its innovative sQuba, a fully functional submersible concept car that cost $1.5 million to build. (Photo by Rinspeed)

Kim Kardashian goes shopping for gummy bears in sheer Gucci bra on October 9, 2017. She paired the risqué outfit with a waist-fitted midi length pencil skirt and clear lucite wedges from Kanye West’s fashion line. (Photo by Splash News and Pictures)

American reality show contestant Courtney Stodden is caught kissing a mystery woman on the beach in Santa Monica, CA on September 16, 2016. Courtney and the mystery brunette couldn't keep their hands of each other and didn't seem to care who saw their antics as they frolicked on the sand. (Photo by Canham/Splash News)

American actress and model Megan Fox nearly busts out of red silk bra as she celebrates 35th birthday with boyfriend Machine Gun Kelly in Santa Monica, California on May 15, 2021. (Photo by Splash News and Pictures)