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.

Girls cry as they get separated from their family at the border line dividing Macedonia and Greece August 21, 2015. At least 1,000 migrants and refugees pressed against Macedonian police lines on the Greek-Macedonian border on Friday and at least 10 people appeared to faint in the crush. People could be heard screaming and medical workers raced to treat those who passed out or were hurt. The crush ensued after police let several hundred through into Macedonia, having kept them out since Thursday under an emergency decree. (Photo by Ognen Teofilovski/Reuters)

A young migrant cries as she waits to cross the Greek-Macedonian border, near the village of Idomeni, Greece March 3, 2016. Thousands of refugees and migrants wait on the border between Greece and Macedonia and about 30,000 refugees and other migrants are stranded in Greece, with 10,000 at the Idomeni border crossing to Macedonia. (Photo by Marko Djurica/Reuters)

A North Korean soldier throws a stone towards a photographer on the banks of the Yalu River in the North Korean town of Sinuiju, opposite the Chinese border city of Dandong October 21, 2006 in Sinuiju, Democratic People's Republic of Korea. (Photo by Cancan Chu/Getty Images)

People enjoy themselves as they dance to Dominican music at a refugee camp for Haitians returning from the Dominican Republic on the outskirts of Anse-a-Pitres, Haiti, September 6, 2015. Dominican officials last month began implementing a controversial immigration program targeting Haitian migrants and Dominican-born people of Haitian descent. The program centers on round-ups and deportations that have triggered concerns about a slow-growing border migration crisis in the poorest country in the Americas. So far about 1,500 people have been deported at a pace of 50 to 100 per day, according to relief officials with access to records supplied by the Dominican government. (Photo by Andres Martinez Casares/Reuters)

A man walks next to a section of the wall separating Mexico and the United States, on the outskirts of Ciudad Juarez, Mexico, November 12, 2016. (Photo by Jose Luis Gonzalez/Reuters)

Artist Terry Border gives new life to old books in his latest series titled Wiry Limbs, Paper Backs. The artist, who is no stranger to breathing new life into inanimate objects, utilizes his handcrafted technique of bending wires to serve as limbs and combines it with a great sense of humor. Each whimsical creation in the ongoing project is a sculptural work that stands on its own, reflecting its respective text.

An activist kicks the shields of the military police officers during a demonstration in the military zone of the 27th infantry battalion in Iguala, Guerrero, January 12, 2015. Activists and relatives of the 43 missing trainee teachers from Ayotzinapa's teacher training college broke into the military zone, located less than a mile from where the students went missing, in an attempt to look for the missing students.The remains of only one of the 43 students has been identified so far. (Photo by Jorge Dan Lopez/Reuters)