Smithsonian National Zoo biologist Leigh Pitsko releases a male lion cub for its swim test in the zoo habitat moat, in Washington May 6, 2014. Four, unnamed ten-week old lion cubs were tested today for their ability to swim and remove themselves from their zoo habitat moat. (Photo by Gary Cameron/Reuters)

Voodoo pilgrims bathe in a waterfall believed to have purifying powers during the annual celebration in Saut d' Eau, Haiti, Saturday, July 16, 2016. Annually, the falls are the site of a large, important religious pilgrimage, during the festival of Our Lady of Carmel, from July 14–16. A Eucharistic rite is held during the festival, as well as various vodou rituals, but the penultimate devotional activity is bathing in the waters of the falls, and asking favors of the Virgin or Erzulie. After bathing, voodoo pilgrims throw away the dresses they wore to the site, and don new clothes for good luck. (Photo by Dieu Nalio Chery/AP Photo)

Pamukkale, Turkey, is home to these terrace pools, formed by the build-up of carbonate mineral from the warm water flowing from the thermal springs above. (Photo by Image Courtesy of Jennifer Hayes/Getty Images)

Reuters multi-award winning photographers are celebrated here in a three part retrospective on the 30th anniversary of the service's launch. They have captured dramatic images illustrating the human tragedy of natural disaster and war as well as the fallout of economic events across the continents, creating iconic images, recognised around the world. Here: an injured soccer fan is carried to safety by a friend after a wall collapsed during violence between fans before the European Cup final between Juventus and Liverpool at the Heysel stadium in Brussels, May 29, 1985. 39 people died, and a further 600 were injured. (Photo by Nick Didlick/Reuters)

Models prepare backstage before a presentation as part of Fashion Weekend Plus Size Summer 2015 collection show in Sao Paulo, July 25, 2015. (Photo by Nacho Doce/Reuters)

“A balancing rock, also called balanced rock or precarious boulder, is a naturally occurring geological formation featuring a large rock or boulder, sometimes of substantial size, resting on other rocks, bedrock or on glacial till. Some formations known by this name only appear to be balancing but are in fact firmly connected to a base rock by a pedestal or stem”. – Wikipedia

Photo: “The Brimham Rocks are balancing rock formations located on Brimham Moor in North Yorkshire, England. The rocks stand at a height of nearly 30 metres in an area owned by the National Trust which is part of the Nidderdale Area of Outstanding Natural Beauty”. – Wikipedia. (Photo by Tee Time Tony)

People wait on a taxi line near Madison Square Garden, Wednesday, September 23, 2015, as a 225-foot-tall hand-painted billboard of Pope Francis stands out at Eighth Avenue in New York. The billboard, designed by Israel Ochoa of DeSales Media, including a photo by photographer Giulio Napolitano, marks the arrival of the pope Thursday. (Photo by Craig Ruttle/AP Photo)

Comic Con fans in costume arrive for the 2nd day of the 2016 New York Comic Con at the Jacob Javits Center on October 7, 2016. The four- day event which runs October 6-9 is the largest pop culture event on the East Coast. (Photo by Timothy A. Clary/AFP Photo)