An artwork of the famous street artist Tvboy is seen on a wall of the House of Culture, which was heavily damaged during Russia's attack on Ukraine, in the town of Irpin, outside Kyiv, Ukraine on January 29, 2023. (Photo by Valentyn Ogirenko/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.

Farmhand Beatrice Jasiewicz (L) looks on as a colleague carries an injured goose on an open field at the Oekohof Kuhhorst organic farm near Berlin on November 24, 2011 in Kuhhorst, Germany. Goose is the traditional Christmas Eve dinner in Germany. (Photo by Sean Gallup/Getty Images)

Buddy Bears are a series of painted, life-size fibreglass bear sculptures originally developed in Berlin, Germany. The first Buddy Bear was created by the German businesspeople Klaus and Eva Herlitz, in cooperation with the sculptor Roman Strobl in 2001.

Talbot Lago T26 Grand sport SWB Saoutichik is displayed for auction during the Retromobile show in Paris, Tuesday, February 3, 2015. 60 rusting motors, which include a vintage Ferrari California Spider, a Bugatti and a very rare Maserati, were found gathering dust and hidden under piles of newspapers in garages and outbuildings at a property in France. The cars were collected from the 1950s to the 1970s by entrepreneur Roger Baillon, who dreamt of restoring them to their former glory and displaying them in a museum, but, his plans were dashed as his business struggled, forcing the sale of about 50 vehicles, to be auctioned off on Feb. 6. (Photo by Jacques Brinon/AP Photo)

Two of 20 skulls to be taken possession of by a delegation from Namibia stand on display at a ceremony at Charite hospital on September 30, 2011 in Berlin, Germany. The skulls are from Herero and Nama tribespeople taken by German colonial forces between 1904 and 1908, when the Germans violently suppressed an uprising in what was then German Southwest Africa, which is today's Namibia, and in the process killed tens of thousand of Herero and Nama. German scientists at the time took the skulls back to Berlin to demonstrate the racial superiority of Europeans over black Africans. Many Namibians demand a formal apology from the German government. (Photo by Sean Gallup/Getty Images)

A red fox sits in front of a Eurofighter Typhoon combat jet on the grounds of the 2014 ILA Berlin Air Show, in Selchow near Schoenefeld, Germany, Thursday, May 15, 2014. The International Aviation and Aerospace Exhibition ILA will take place from May 20 until May 25, 2014. (Photo by Patrick Pleul/AP Photo/DPA)