“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)

A shot of Pu'uo crater, the main source of lava from Kilauea, taken from a helicopter in Kilaura, Hawaii. (Photo by Kirk Aeder/Barcroft Media)

Hedi Xandt imagines impressive sculptures. Mixing styles and materials with talent, the artist invites us to discover his dark and intense universe.

Lightning strikes during a storm over the Ionian Sea in Calabria, Italy on June 27, 2016. (Photo by Alfonso Di Vincenzo/Pacific Press/Rex Features)

Robot pianist Teo Tronico performs at the World Robot Conference (WRC) 2017 at Etrong International Exhibition & Convention Center on August 22, 2017 in Beijing, China. The World Robot Conference 2017 is held from August 23 to 27 in Beijing. (Photo by Liu Guanguan/China News Service/VCG via Getty Images)

Mercury and Maia, fueled and overhauled, are waiting in the Tay at Dundee, for favorable weather to start the flight to the Cape, a distance of 6,370 miles. The composite machine moored in the Tay River, at Dundee, on September 23, 1938. (Photo by AP Photo)

Friends outside the convention center during opening day of the annual Comic-Con International in San Diego, California, United States July 21, 2016. (Photo by WENN/SIPA Press)

Towie star Pete Wicks and Chloe Sims seen leaving Pride of Britain Awards held at Grosvenor House on October 29, 2018 in London, England. (Photo by Splash News and Pictures)