A gaucho is unseat by a wild horse during the annual celebration of Criolla Week in Montevideo, March 30, 2015. Throughout Easter Week, “gauchos”, the Latin American equivalent of the North American cowboy, from all over Uruguay and neighboring Argentina and Brazil will visit Montevideo to participate in the Criolla Week to win the best rider award. The competition is held from March 29 to April 5 this year. (Photo by Andres Stapff/Reuters)

Competitors pose backstage during the Arnold Classic South America bodybuilding event in Sao Paulo, Brazil, April 22, 2017. (Photo by Nacho Doce/Reuters)

“Senorita” – California-native fashion model Tiffany Keller heats up photographer Vladimir Marti’s lens for the April 2013 issue of Marie Claire Latin America. The dark-haired beauty poses in the city of San Miguel de Allende, Mexico, donning sultry styles from designer labels selected by fashion editor and stylist Gerard Angulo. (Photo by Vladimir Marti)

Participants in the Miss Pole Dance South America 2013 competition pose in front of the obelisk in Republica Square in downtown Buenos Aires on November 22, 2013 ahead of the contest to be held on November 23 and 25 in the city. (Photo by Juan Mabromata/AFP Photo)

In the build-up to Halloween those hunting for a real-life ghost town need look no further than this haunting spot. Bodie, California, USA – which requires special access to photograph at night – is one of the best preserved ghost towns in America, still featuring the abodes of the former miners who inhabited it more than 100 years ago. Here: Bodie, California, a real-life ghost town. (Photo by Matthew Christopher/Caters News Agency)

Migrants ride on top of a northern bound train toward the US-Mexico border in Juchitan, southern Mexico, Monday, April 29, 2013. Migrants crossing Mexico to get to the U.S. have increasingly become targets of criminal gangs who kidnap them to obtain ransom money. (Photo by Eduardo Verdugo/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.

Members of the Oath Keepers and general public return fire during a simulated attack as they take part in a tactical training session in northern Idaho, U.S. October 1, 2016. In April 2015 Reuters photographer Jim Urquhart was assigned to cover the Oath Keepers during a tour of the Sugar Pine gold mine in Oregon after the group of former cops, military, firefighters and other first responders had risen to prominence during a standoff in Nevada over land rights. (Photo by Jim Urquhart/Reuters)