In this picture taken on Thursday, December 1, 2016, an Iranian woman covers herself with a blanket due to the cold, while visiting Khour salt lake during her tour of the Mesr desert about 305 miles (500 kilometers) southeast of the capital Tehran, Iran. Deserts make up parts of Iran which have recently become tourist destination for young Iranians looking for a break on their weekend. The increase in tourists to the desert has stimulated economic growth in the area. (Photo by Ebrahim Noroozi/AP Photo)

Dan McManus and his service dog Shadow hang glide together outside Salt Lake City, Utah, July 22, 2013. McManus suffers from anxiety and Shadow's presence and companionship help him to manage the symptoms. The two have been flying together for about nine years with a specially made harness for Shadow. (Photo by Jim Urquhart/Reuters)

Jordan Mann (R) falls into the water as he and Jordan Cross compete in the first round of Men's 3000 Meters Steeplechase during day four of the 2020 U.S. Olympic Track & Field Team Trials at Hayward Field on June 21, 2021 in Eugene, Oregon. (Photo by Patrick Smith/Getty Images)

Bowie Snow runs in the tulips at Strawberry Fields, Lifton, Devon on April 13, 2025. The South West's largest tulip festival takes place across April, showcasing 250,000 Tulips with over 40 varieties across three acres at Strawberry Fields in UK. (Photo by William Dax/South West News Service)

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 goat wearing a sweater walks in a field in New Delhi, India, Thursday, January 17, 2019. (Photo by Altaf Qadri/AP Photo)

Carrion crows sit on poles around a field on the outskirts of Frankfurt, Germany, early Monday, June 26, 2023. (Photo by Michael Probst/AP Photo)