Models promote a condom brand at the first Shenzhen s*x Culture Festival on September 21, 2007 in Shenzhen of Guangdong Province, China. The festival aims to increase awareness about reproductive health and popularise s*x education. (Photo by China Photos/Getty Images)

A migrant prays on his knees after boarding the Migrant Offshore Aid Station (MOAS) rescue ship Topaz Responder around 20 nautical miles off the coast of Libya, June 23, 2016. (Photo by Darrin Zammit Lupi/Reuters)

A man carries his wife on his back as they make their way with their luggage along a flooded tunnel to catch their train, after heavy rainfall hit Jinhua, Zhejiang province, China, July 21, 2015. (Photo by Reuters/China Daily)

A containment shelter for the damaged fourth reactor (L) and the New Safe Confinement (NSC) structure (R) at the Chernobyl Nuclear Power Plant are seen from Ukraine's abandoned town of Pripyat, Ukraine, April 22, 2016. (Photo by Gleb Garanich/Reuters)

Factory landlord Lawrence Taylor (L), portraying a Colour Sergeant from the King's Royal Rifle Corps, part of the Rifles Living History Society, performs a drill with Connor Young (R) of the Queen's Own Royal West Kent Regiment Living History Group as they recreate the life of a First World War soldier at the Eden Valley Museum in Edenbridge in southeast England May 10, 2014. Lawrence has always had an interest in military history and specifically “The Rifles” – his veteran father's WWII regiment. When he became a re-enactor he chose not to re-enact WWII as many of the veterans are still alive, and he felt uncomfortable as he remembers his father would have flashbacks and nightmares about the war. United by a fascination with military history and a fondness for dressing up, groups such as the Rifles Living History Society and the Queen's Own Royal West Kent Regiment Living History Group get together to recreate aspects of life during the First World War. Reuters photographer Luke MacGregor photographed members of the groups, both as they took part in living history events and at their day jobs. (Photo by Luke MacGregor/Reuters)

“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

Bottlenose dolphins swim over visitors in water tank at the Hakkeijima Sea Paradise aquarium-amusement park complex in Yokohama, southwest of Tokyo, Tuesday, July 21, 2015. Temperatures in Tokyo's metropolitan area neared around 96 degree Fahrenheit, or 35 degree Celsius, on Tuesday. (Photo by Shuji Kajiyama/AP Photo)

A woman has her hair blown by the wind during a snowstorm in Quebec City, on December 22, 2013. (Photo by Mathieu Belanger/Reuters)