“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)

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 woman poses for a photograph in front of a 3D painting at HK 3D Museum in Hong Kong June 26, 2014. (Photo by Tyrone Siu/Reuters)

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

Contestants congratulate Chelsea Morgensen (R) of Hollywood, California as she is crowned Miss Hooters International 2017 during the 21st Annual Hooters International Swimsuit Pageant at The Pearl concert theater at Palms Casino Resort on July 12, 2017 in Las Vegas, Nevada. (Photo by Alamy Stock Photo)

A woman carries her child as she watches Mount Sinabung volcano spewing thick volcanic ash, as seen from Karo on July 21, 2017. Sinabung roared back to life in 2010 for the first time in 400 years, after another period of inactivity it erupted once more in 2013, and has remained highly active since. (Photo by Gatha Ginting/AFP Photo)

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)