A mechanic assembles a BMW C evolution electric maxi-scooter at the BMW Berlin motorcycle plant February 23, 2015. The storage capacity of the BMW C evolution's high-voltage 8 kWh battery provides a range of up to 100 kilometres and a maximum speed of 120 km/h. (Photo by Fabrizio Bensch/Reuters)

Shaolin monks pose for a photograph in Chinatown on February 23, 2015 in London, England. The monks practice Shaolin Kung Fu which is believed to be the oldest institutionalised style of kung fu and are demonstrating their skills while in the UK. (Photo by Carl Court/Getty Images)

Michael O’Neill won a prize in animal portraits with fry of a peacock bass hovering around their mother for protection against predators in South Florida. (Photo by Michael Patrick O'Neill/2016 National Geographic Nature Photographer of the Year)

An elephant with a shackled leg is pictured at the Hanoi Zoo in Hanoi on August 16, 2023. Legs in iron chains and unable to roam freely, the treatment of two elderly elephants at the Hanoi public zoo has drawn outrage from animal lovers across Vietnam. (Photo by Nhac Nguyen/AFP Photo)

The sunrises at 04.25am at St Mary's Lighthouse in Whitley Bay, on the North East coast of England on Tuesday, June 20, 2023, the day before Summer Solstice – the longest day of the year. (Photo by Owen Humphreys/PA Images 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.

Tom Nevins guts a feral pig sow during hunting on Silver Plains Station on October 8, 2011 outside of Coen, Australia. Feral pigs are recognised as environmental and agricultural pests reported to have a population of up to 23.5 million over around half of Australia. The Cooktown Hog Hunt is held annually with this year's hunting window open from registration at 2pm on Friday to the end of weigh in at 2pm on Sunday afternoon. (Photo by Mark Kolbe/Getty Images)