In this aerial view fishing boats are seen on the shore of the Lake Malawi at the Senga village on May 20, 2019 in Senga, Malawi. Hundreds of local traders gather each morning and afternoon at Senga, but fish populations are falling in Lake Malawi, Africa's third largest body of freshwater. (Photo by Gianluigi Guercia/AFP Photo)

A streaker races across the field and is caught by security during the Super Rugby match between New Zealand's Highlanders and South Africa's Sharks at Forsyth Barr Stadium in Dunedin on February 7, 2020. (Photo by Marty Melville/AFP Photo)

“People of the River”. This is a Karo tribe family; father, mother, two sisters and two brothers. The tribe, who live along the Omo River in east Africa, incorporate rich symbolism into their rituals by using ornate body art, headdresses and body scarification to express beauty and significance. (Photo by Jatenipat Ketpradit/International Portrait Photographer of the Year)

Nuns react at the arrival of Pope Francis at the St. Mary's school to attend a meeting of clergy and religious in Nairobi, Kenya, 26 November 2015. Pope Francis is on a six days visit that will take him to Kenya, Uganda and the Repulic of Central Africa from 25 to 30 November. (Photo by Daniel Dal Zennaro/EPA)

Izelle Nair, 39, the instructor at the Merschool poses for a portrait in her mermaid attire at the centre in Kayalami, Midrand, South Africa on June 3, 2022. Mermaiding is a fast growing sport world wide and includes several skills such as monofin swimming, sculling, tricks and breath hold. (Photo by Marco Longari/AFP Photo)

Australian rider Jack Miller (on tarmac) of Red Bull KTM Factory Racing and teammate Brad Binder of South Africa fall after a crash during the Malaysia Motorcycling Grand Prix 2024 at the Petronas Sepang International Circuit, in Sepang, Malaysia, 03 November 2024. (Photo by Fazry Ismail/EPA)

Zulu maidens dance during the memorial service for King Goodwill Zwelithini in Nongoma, South Africa, March 18, 2021. King Goodwill Zwelithini died on March 12, 2021 in the eastern city of Durban, aged 72, after weeks of treatment for a diabetes-related illness. (Photo by Phill Magakoe/Pool via 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.