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 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)

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)

“The Victoria Falls or Mosi-oa-Tunya is a waterfall located in southern Africa on the Zambezi River between the countries of Zambia and Zimbabwe. A famous feature is a naturally formed pool known as the Devil's Pool, near the edge of the falls, accessed via Livingstone Island in Zambia. When the river flow is at a certain level, usually during the months of September to December, a rock barrier forms a pool with little current; some people swim in the pool. Occasional deaths have been reported when people slip over the edge of the rock barrier”. – Wikipedia

Photo: Devil's Pool – Victoria Falls, Zambia. (Photo by Siena College Study Abroad)

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)

Kaia Gerber walks the runway during the Moschino fashion show as part of Milan Fashion Week Fall/Winter 2020-2021 on February 20, 2020 in Milan, Italy. (Photo by Pietro D'Aprano/Getty Images)

French actress Audrey Tautou arriving to the Balmain show as part of Paris Fashion Week Fall/Winter 2020/2021 on February 28, 2020 in Paris, France. (Photo by Meryl Curtat/SIPA Press)