Russian army servicewomen march during the Victory Day military parade at the Palace Square in St. Petersburg, Russia, Thursday, May 9, 2024, marking the 79th anniversary of the end of World War II. (Photo by Dmitri Lovetsky/AP Photo)

A volunteer in the Kurdish Community Protection Forces guards wheat fields from fire or looting around the town of Tarbesbeyeh, also known as al-Qahtaniyah in Arabic, in northeastern Syria's Hasakeh Governorate near the Turkish border on May 30, 2024. (Photo by Delil Souleiman/AFP Photo)

American singer-songwriter and rapper Janelle Monáe at Richie Akiva's 10th Annual “The After” Met Gala After Party held at Casa Cipriani on May 6, 2024 in New York, New York. (Photo by Daniel Zuchnik/WWD via Getty Images)

Member of Unifrance delegation Swiss actress Souheila Yacoub arrives for the screening of the film “Le Comte de Monte-Cristo” (The Count of Monte-Cristo) at the 77th edition of the Cannes Film Festival in Cannes, southern France, on May 22, 2024. (Photo by Loic Venance/AFP Photo)

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.

Lea Michele attends The Metropolitan Museum of Art's Costume Institute benefit gala celebrating “Charles James: Beyond Fashion” on Monday, May 5, 2014, in New York. (Photo by Charles Sykes/Invision/AP Photo)

An Amur tiger walks across a passageway after a news conference at the Philadelphia Zoo, Wednesday, May 7, 2014, in Philadelphia. The see-through mesh pathway called Big Cat Crossing is part of a national trend called animal rotation that zoos use to enrich the experience of both creatures and guests. (Photo by Matt Slocum/AP Photo)

A helicopter of the Food and Agriculture Organization of the United Nations (FAO) flies through millions of Locusts as spreads pesticide to fight against a swarm of locusts threatening to reach Amparihibe village on May 7, 2014 in Tsiroanomandidy, Madagascar. FAO mission is to fight the locust's swarm with an insecticide. (Photo by AFP Photo/RIJASOLO)