A group of Japanese schoolgirls marching in formation during a school visit to the third regiment to experience the soldier's way of life. (Photo by Fox Photos/Getty Images). Circa 1938

Bob Steele, of Jefferson, Texas, positions his bears during The Great Bear Show at the Dubuque (Iowa) County Fair on July 25, 2012. (Photo by Jessica Reilly/Telegraph Herald)

A man jokingly poses with a new installation of British graffiti artist Banksy's art in New York, October 20, 2013. (Photo by Carlo Allegri/Reuters)

Palestinian children warm themselves by a fire on a stormy day at Shati (beach) refugee camp in Gaza City January 18, 2016. (Photo by Mohammed Salem/Reuters)

A man exercises in the early morning on a hilltop overlooking Kabul, Afghanistan March 3, 2016. (Photo by Mohammad Ismail/Reuters)

Veteran racehorse Morestead models the world's first authentic Harris Tweed suit designed for a racing horse, which has been specially commissioned by William Hill to celebrate the opening of this year's Cheltenham Festival on March 15, 2016 in the U.K. (Photo by Joe Pepler/Rex Features/Shutterstock)

Schoolchildren play music to entertain and inspire people on their way home from work Tuesday, March 29, 2016 in Pyongyang, North Korea. North Korea has called a 70-day loyalty drive areas of a major congress of the ruling party scheduled for early May and everyone from students to coal miners have been mobilized nationwide to demonstrate their devotion to the leadership. (Photo by Eric Talmadge/AP Photo)

“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)