Customers take photos of a snake at the Tokyo Snake Center, a snake cafe, in Tokyo's Harajuku shopping district August 14, 2015. The cafe has on display 35 non-venomous snakes of 20 different breeds. Open six days a week, the cafe allows customers to enjoy food and beverages while watching a small snake slither around in a cage on their table for a 1,000 yen (8.04 dollars). By paying an additional fee, customers get to hold and pet the snake. (Photo by Toru Hanai/Reuters)

The tempestuous stellar nursery called the Carina Nebula, located 7,500 light-years away from Earth in the southern constellation Carina. (Photo by Reuters/NASA)

People participate in a Christmas Day dip on Brighton beach in southern England, Britain, December 25, 2021. (Photo by Hannah McKay/Reuters)

Palestinians react at the site of an Israeli strike on a house, in Khan Younis, in the southern Gaza Strip on October 24, 2023. (Photo by Ibraheem Abu Mustafa/Reuters)

A tattoo artist applying ink on a girl' s arm during the 2017 Moscow Tattoo Festival at Moscow' s Amber Plaza Shopping Center in Moscow, Russia on April 1, 2017. Tattoo artists from all over the world take part in the event. The festival' s program includes a tattoo contest, body taping art marathon, masterclasses, round table discussions and conferences. (Photo by Valery Sharifulin/TASS)

Passengers from the ferry sinking off South Korea's southern coast are rescued by the South Korean Coast guard in the water off the southern coast near Jindo, south of Seoul, on April 16, 2014. Almost 300 people were missing after a ferry sank off South Korea on Wednesday, the coastguard said, in what could be the country's biggest peacetime disaster in nearly 20 years. (Photo by AP 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.