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)

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 Romanian female soldier adjusts her helmet before taking part in weapons training with US Marines female counterparts at the Capu Midia Surface to Air Firing Range, on the Black Sea coast in Romania, Monday, March 20, 2017. About 1,200 US and Romanian troops take part in the Spring Storm 17 exercise, meant to simulate defense of the Romanian Black Sea coastline and urban areas. (Photo by Vadim Ghirda/AP Photo)

A police officer who was injured when falling of a horse during scuffles with demonstrators at Downing Street during a Black Lives Matter march in London, Saturday, June 6, 2020, is dragged by colleagues, as people protest against the killing of George Floyd by police officers in Minneapolis, USA. Floyd, a black man, died after he was restrained by Minneapolis police while in custody on May 25 in Minnesota. (Photo by Frank Augstein/AP Photo)

Republic of Korea Air Force's (ROKAF) aerobatic unit “Black Eagles” maneuver their T-50B aircraft as they perform an air show at Clark Air Base on March 03, 2024 in Pampanga, Philippines. The Republic of Korea Air Force's (ROKAF) aerobatic unit “Black Eagles” is in the Philippines to conduct a series of air shows to mark the 75th anniversary of diplomatic relations between the Philippines and South Korea. (Photo by Ezra Acayan/Getty Images)

Four-year-old Chinese girl Jiaxue, who suffers from hairy black moles, sits on a bed at home November 4, 2006 in Changchun of Jilin Province, China. Jiaxue was born with black moles covering part of her back, breast, neck and face. Experts said the condition may be an atavism. (Photo by China Photos/Getty Images)