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 graphic designer has produced a haunting look at what the world’s most famous landmarks would look like if they were hit by a severe drought. Joel Krebs has intricately dried up hot spots such as the Tower Bridge in London, the Capitol in Washington, D.C., Niagara Falls and Machu Picchu. Here: Niagara Falls, Canada, after severe drought. (Photo by Joel Krebs/Caters News)

A Kashmiri Muslim woman balances on a water pipe before collecting water at Dasilpora village on March 22, 2018. World Water Day is held annually on 22 March as a means of focusing attention on the importance of freshwater and advocating for the sustainable management of freshwater resources. (Photo by Tauseef Mustafa/AFP Photo)

This photo taken on November 7, 2021 shows a panda falling from a platform as it plays in its enclosure after snowfall in Xian in China's northern Shaanxi province. (Photo by AFP Photo/China Stringer Network)

Model Winnie Harlow wears a creation as part of the John Richmond men's Fall-Winter 2019-20 collection, that was presented in Milan, Italy, Sunday, January 13, 2019. (Photo by Antonio Calanni/AP Photo)

A model presents a creation by Andrea Crews as part of their Fall/Winter 2019-2020 collection show during Men's Fashion Week in Paris, France, January 19, 2019. (Photo by Gonzalo Fuentes/Reuters)

Model Ming Xi falls as she presents a creation during the 2017 Victoria's Secret Fashion Show in Shanghai, China, November 20, 2017. (Photo by David Fisher/Rex Features/Shutterstock)

Rihanna attends the Balmain show as part of the Paris Fashion Week Womenswear Fall/Winter 2014-2015 on February 27, 2014 in Paris, France. (Photo by Dennis Leupold/The Guardian)