“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)

Mug shot of De Gracy (sic) and Edward Dalton. Details unknown. Central Police Station, Sydney, around 1920. (Photo by NSW Police Forensic Photography Archive, Justice & Police Museum, Histiric Houses Trust of NSW)

NASA's DHC-3 Otter plane flies in Operation IceBridge-Alaska surveys of mountain glaciers in Alaska in this image released on September 18, 2014. Over the past few decades, average global temperatures have been on the rise, and this warming is happening two to three times faster in the Arctic. (Photo by Chris Larsen/Reuters/NASA/University of Alaska-Fairbanks)

A man performs a split as he practices Kung Fu at Beihai Park in Beijing, China August 20, 2017. (Photo by Reuters/China Stringer Network)

Using digital editing, designer Anton Repponen places Manhattan buildings in desolate landscapes, “inviting viewers to see them as if for the first time”. Here: 8 Spruce Street/New York By Gehry. Photo by Anton Repponen/The Guardian)

American artists have drawn criticism after making stunning, intricate sculptures by pouring hot liquid aluminium into anthills.

A model sports beachwear designed by Gottex during the Canal Catwalk fashion show with clothing dedicated to Kate, Duchess of Cambridge, during the first edition of the World Fashion Fair in Amsterdam, Netherlands, Thursday, May 21, 2015. (Photo by Peter Dejong/AP Photo)

Annual celebration of Dinagyang festival of Iloilo, Philippines. (Photo by Raniel Jose Castañeda/Sony World Photography Awards)