“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 Colombia fan clearly regrets invading the pitch as she is chased by a large security guard during the International Friendly match between Australia and Colombia at Craven Cottage on March 27, 2018 in London, England. (Photo by Charlotte Wilson/Offside/Getty Images)

This 1931 Stutz DV-32 convertible sedan has 66,000 miles on its odometer and its original leather luggage awaits its first complete restoration Tuesday, March 5, 2013 at L'Cars Automotive Specialties in Cameron, Wis. The company which does high-end restoration and customization work classic cars that have won awards at the world-renowned Pebble Beach Concours d'Elegance. Winning cars include a 57c Bugatti, Rolls Royce PIII V12, V12 Aero coupe, T44 Bugatti, T55 Bugatti, T38A Bugatti, Mercedes Benz 290 Roadster, Rolls Royce Silver Ghost, T57 Bugatti, 1929 Duesenberg J, Mercedes Benz 540K cabriolet, Talbot Teardrop and a 1931 V16 Cadillac convertible. (Photo by Mark Hoffman)

A novice Bhutanese monk sleeps after hours of prayer waiting for class to be over at the Dechen Phodrang monastery October 18, 2011 in Thimphu, Bhutan. The monks average about 10 hours of study a day waking up at 5:00am. (Photo by Paula Bronstein/Getty Images)

US marines watch the mushroom cloud from an atomic explosion rise above the Yucca flats, Nevada during a US nuclear weapons test. (Photo by Keystone/Getty Images). USA, 1945

Dried and shrivelled corpses, some fully clothed and some in coffins, line the wall of a vault of the Pantheon Cemetery on the summit of Cerro del Trozado in Mexico. They were removed from the crypts because of non-payment of cemetery fees. The hot dry air stopped the bodies from rotting. Most of them were placed here between the turn of the century and WW I. (Photo by Three Lions/Getty Images). Circa 1955

Penitentes, or nieves penitentes (Spanish for “penitent-shaped snows”), are a snow formation found at high altitudes. They take the form of tall thin blades of hardened snow or ice, closely spaced with the blades oriented towards the general direction of the sun.

People fly kites during the 2017 Pyostroye Nebo kite festival in Tsaritsyno Park in Moscow, Russia on August 27, 2017. (Photo by Asya Dobrovolskaya/TASS)