Sonny Colbrelli of Italy celebrates winning the men's Paris Roubaix, a 258 kilometer (160.3 miles) one-day-race cycling race, at the velodrome in Roubaix, northern France, Sunday, October 3, 2021. (Photo by Vincent Kalut/Pool Photo via AP Photo)

A tourist splashes water on the frozen Songhua River on December 18, 2023 in Harbin, Heilongjiang Province of China. The water immediately freezes into ice in the frigid air. (Photo by VCG/VCG via Getty Images)

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.

Dragon boat racers prepare for the fancy dress race on July 5, 2015 in Hong Kong, Hong Kong. The Hong Kong Dragon Boat Carnival will be staged from 3 July 2015 (Friday) to 5 July 2015 (Sunday). The carnival featured two key programmes: the CCB (Asia) Hong Kong International Dragon Boat Races in Victoria Harbour and the San Miguel BeerFest at the UC Centenary Garden in East Tsim Sha Tsui. (Photo by Taylor Weidman/Getty Images for Hong Kong Images)

British housewives toss pancakes in skillets as they run through the streets of Olney, England, in the community's annual race which follows a 500-year-old tradition, February 6, 1951. Mrs. Isabel Dix, 22, extreme right, won the race covering the 415 yards from the Parish pump to the door of Sts. Peter and Paul church in one minute, 12.1 seconds. (Photo by AP Photo)

Marta Garcia (R) of Spain loses the champgane bottle standing on the podium next to winner Jamie Chadwick of Great Britain after the first race of the W Series at Hockenheimring on May 04, 2019 in Hockenheim, Germany. W Series aims to give female drivers an opportunity in motorsport that hasn’t been available to them before. The first race of the series, which encompasses six rounds on the DTM support programme, is at the Hockenheimring on May 3rd and 4th. (Photo by Kai Pfaffenbach/Reuters)

Boys and younger men from the Ilosvai Selymes Peter folk dance group pour buckets of cold water on a girl as they attend the traditional watering of local girls on Easter Monday in Komarovce, Velke Trakany, Slovakia on April 10, 2023. During Easter Holy Week, the ancient tradition of Easter sprinkling known as “watering of the girls” when Hungarian boys visit their female friends, recite poems, and pour water on them, and in exchange the girls offer the boys food and drink. (Photo by Robert Nemeti/Anadolu Agency via Getty Images)

Racing in the XOD class during day six of the Aberdeen Asset Management Cowes Week on August 11, 2011 in Cowes, England. (Photo by Alan Crowhurst/Getty Images)