A combination photo shows various popular street foods under $6 from various hawker food stalls and eateries in Singapore, taken between July 28 to 31, 2016. Top row (L to R) bak chor mee, soya sauce chicken; Middle row (L to R) laksa, hokkien mee, nasi lemak, ice kachang; Bottom row (L to R) rojak, roti prata and satay. (Photo by Edgar Su/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.

A grey squirrel looks for some food from a girl in the Botanic Gardens in Glasnevin, Dublin, Ireland on April 3, 2023. (Photo by Damien Eagers/The Irish Times)

These young sloth bears hitch a ride on their mother's back as she forages for food in the Ranthambhore Tiger Reserve in the Indian state of Rajasthan in May 2023. (Photo by Aditya Singh/Solent News)

Revelers play in tomato pulp during the annual “La Tomatina” food fight festival in Bunol, Spain on August 30, 2023. (Photo by Eva Manez/Reuters)

A Mongolian Bloody Mary, made with pickled sheep eyeballs and tomato juice, is displayed at the Disgusting Food Museum in Malmo, Sweden November 1, 2018. (Photo by Mikael Nilsson/Reuters)

Two girls perform with their body painted for money fort purchasing food for breaking fasting in Bekasi, West Java, Indonesia on April 25, 2020, during the holy month of Ramadan. (Photo by Rezas/AFP Photo)

A woman carries food for her cattle past storks standing atop of one of the largest disposal sites in northeast India at the Boragaon area of Guwahati on June 4, 2020. (Photo by Biju Boro/AFP Photo)