A girl in a vamire costume poses for pictures during the traditional park picnic on the first day of the annual Wave-Gotik Treffen, or Wave and Goth Festival, on May 17, 2013 in Leipzig, Germany. The four-day festival, in which elaborate fashion is a must, brings together over 20,000 Wave, Goth and steam punk enthusiasts from all over the world for concerts, readings, films, a Middle Ages market and workshops. (Photo by Marco Prosch)

A driver competes in his tractor during the Tractor Pulling Euro Championships in the western German town of Fuechtorf September 9, 2012. Eighty teams from across Europe participated in the two-day competition where high-powered tractor prototypes must pull a trailer down a 100-metre (328 ft) track as far as possible. (Photo by Ina Fassbender/Reuters)

Winner. “This was taken in the South Ari Atolls, Maldives, as the south-west monsoon season was setting in. It features my partner – and dive buddy – Emma after surfacing at the end of the last dive of the day to find 1.5 metre swells and dark monsoon clouds. MICK RYAN, JUDGE: This beautiful portrait of a diver in an ocean swell below a menacing sky stands out this month for its emotional and elemental beauty. It is a reminder that while we may play among nature we are always dwarfed by its power and must be constantly on our guard”. (Photo by Simon Dunn/The Guardian)

In a photo taken on June 5, 2017 a traffic security officer stands on duty at an intersection in Pyongyang. Officially known as traffic security officers but universally referred to as traffic ladies, they are chosen for their looks in a society that remains traditionalist in many respects. They must leave the role if they marry, and have a finite shelf-life, with compulsory retirement looming at just 26. (Photo by Ed Jones/AFP Photo)

Ukrainian state emblem is seen on a gun's holster as soldiers guard naval base in the village of Novoozernoye, some 91 km west of Crimean capital Simferopol, Ukraine, on Monday, March 3, 2014. Ukraine says Russian forces controlling the strategic region of Crimea are demanding that the crew of two Ukrainian warships in Sevastopol's harbor must surrender. (Photo by Ivan Sekretarev/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)

In this May 14, 2016 photo, children wearing their school backpacks climb on a cliff using a bamboo ladder on their way home from school in Zhaojue county, southwest China's Sichuan province. A village in China's mountainous west where schoolchildren must climb an 800-meter (2,625-foot)-high bamboo ladder secured to a sheer cliff face may get a set of steel stairs to improve it's safety. (Photo by Chinatopix via AP Photo)

Afghan dogs fight during the weekly dog fight in Kabul, Afghanistan, 17 February 2017. Under the Taliban dog fighting was forbidden, but since their fall it has become a major source of entertainment for hundreds of Afghans, where bets can amount to thousands of dollars and the dogs, which must be over one year old, are well-cared for by their owners and fed milk, butter and meat. (Photo by Hedayatullah Amid/EPA)