Doris Dean of Chicago, Ill., sits with her gun shortly after she won a 50 meter, 40-shot event for women with a perfect 400 score at the National Rifle Association (NRA) matches at Camp Perry, near Toledo, Ohio, September 7, 1941. (Photo by AP Photo/DW)

A hyena cub got a mouthful from his mum after it appears he got a right telling off. Michael Raddall, a animal enthusiast and wildlife photographer from South Africa, snapped the mum and cub at the Timbavati game reserve in South Africa while on safari at the Umlani Bush camp. (Photo by Michael Raddall/Caters News Agency)

Jared Leto, holding a model of his own head, attends The Metropolitan Museum of Art's Costume Institute benefit gala celebrating the opening of the “Camp: Notes on Fashion” exhibition on Monday, May 6, 2019, in New York. (Photo by Charles Sykes/Invision/AP Photo)

A U.S. Marine kneels beside a Multi-Utility Tactical Transport ( MUTT) during a patrol as part of Rim of the Pacific (RIMPAC) 2016 an exercise held at Camp Pendleton, California United States, July 13, 2016. (Photo by Mike Blake/Reuters)

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.

In this photograph taken on January 29, 2017, Afghan members of a wushu martial arts group led by trainer Sima Azimi (C), 20, pose for a photograph at the Shahrak Haji Nabi hilltop overlooking Kabul. Afghanistan's first female wushu trainer, Sima Azimi, 20, is training 20 Afghan girls aged between 14 – 20 at a wushu club in Kabul, after learning the sport while living as a refugee in Iran. (Photo by Wakil Kohsar/AFP Photo)

In this March 22, 1975 file photo, a refugee clutches a baby as a government helicopter gunship carries them away near Tuy Hoa, Vietnam, 235 miles northeast of Saigon. They were among thousands fleeing from Communist advances. AP Photographer Nick Ut will be retiring from the AP in March 2017 after 51 years of taking photographs from the front lines of the Vietnam War to the red carpets of Hollywood. (Photo by Nick Ut/AP Photo)