A black bear cub performs for its mum at the Pocosin Lakes National Wildlife park in North Carolina, US in January 2022. (Photo by Jennifer Hadley/Animal News Agency)

Scarlett Johansson, Florence Pug, Rachel Weisz and David Harbour star in the action spy thriller “Black Widow”. Pictured: English actress Florence Pugh as Yelena. (Photo by Splash News and Pictures)

American singer-songwriter Katy Perry in the second decade of June 2024 posed in a white bra top with heavy black metallic leg armour to announce her new single Woman’s World. (Photo by Katy Perry/Instagram)

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.

Vintage wine bottles dated from 1946 lay down in the wine cellar of the Massandra winery near Yalta, 28 March 2014 (Yalta is a resort city on the north coast of the Black Sea in the Autonomous Republic of Crimea, a territory recognized by a majority of countries as part of Ukraine and incorporated by Russia as the Republic of Crimea). Massandra winery has one of the largest wine collections in the world. (Photo by Sergei Ilnitsky/EPA)

A policewoman uses her mobile phone as navy honor guards stand near of a World War Two memorial during celebrations to mark Victory Day in the Black Sea port of Odessa May 9, 2014. Ukraine celebrates the 1945 victory over Nazi Germany during World War Two on May 9. (Photo by Gleb Garanich/Reuters)

Japanese researchers have sparked hopes of finding a cure for human baldness after successfully growing hair on hairless mice by implanting follicles created from stem cells, Agence France Presse reports. A picture taken on April 13, 2012 and released by the Tsuji Lab Research Institute for Science and Technology of the Tokyo University of Science shows a hairless mouse with black hair on its back at the laboratory in Noda, Chiba Prefecture. (Photo by Tokyo University of Science via AFP)

Participants dance and climb on an art installation as approximately 70,000 people from all over the world gather for the 30th annual Burning Man arts and music festival in the Black Rock Desert of Nevada, U.S. August 31, 2016. (Photo by Jim Urquhart/Reuters)