A girl feeds the new-born kitten as the family, living in tent city, adopted two kittens, found under the rubble, after 7.7 and 7.6 magnitude earthquakes hit in Hatay, Turkiye on March 15, 2023. (Photo by Sergen Sezgin/Anadolu Agency via Getty Images)

A Tibetan girl is reflected in a mirror, as she gets ready for her performance during an event organised to mark the 88th birthday celebration of their spiritual leader, the Dalai Lama in Kathmandu, Nepal on July 6, 2023. (Photo by Navesh Chitrakar/Reuters)

A girl cools off in a public fountain in Vilnius, Lithuania, Wednesday, August 16, 2023. The heat wave continues in Lithuania as temperatures rise to as high as 32 degrees Celsius (89.6 degrees Fahrenheit). (Photo by Mindaugas Kulbis/AP Photo)

A girl plays at the West Side Hallo Fest, a Halloween festival in Bucharest, Romania, Friday, October 27, 2023. Tens of thousands streamed last weekend to Bucharest's Angels' Island peninsula for what was the biggest Halloween festival in the Eastern European nation since the fall of Communism. (Photo by Vadim Ghirda/AP Photo)

Jesy Nelson, Leigh-Anne Pinnock, Jade Thirlwall and Perrie Edwards of English girl group Little Mix celebrate getting number 1 UK single backstage at Echo Arena on July 18, 2015 in Liverpool, England. (Photo by Ollie Millington/Redferns)

To an outsider, their passion is at times illegal and often on the verge of life and death. But climbing rooftops of high-rise buildings and exploring abandoned facilities is in the blood of these young Muscovites. The small group calls itself “Rudex”, which stands for “roof and decay exploration”, and is akin a Western youth craze known as urbex or “urban exploration” of man-made structures. Here: Urban explorer Vad Him of Rudex team jumps whilst on a rooftop in Moscow, Russia, August 14, 2017. (Photo by Maxim Shemetov/Reuters)

Taiwanese artist Hank Cheng poses with his miniature model of Taipei street scenes, in New Taipei City, Taiwan on June 17, 2018. While some of the vehicles used in Cheng's street scenes are bought in shops, all the buildings and small details like the magazines and the furniture for his model houses are created from scratch. (Photo by Tyrone Siu/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.