Participants play with water guns during the Sinchon Water Gun Festival in Seoul, South Korea, July 9, 2016. (Photo by Kim Hong-Ji/Reuters)

A woman rides a custom bike during "Bike Kill 12" in the Brooklyn borough of New York City, October 31, 2015. "Bike Kill" is an annual gathering of builders and riders of home-made bicycles that culminates in a tall bike jousting competition. (Photo by Stephanie Keith/Reuters)

Thousands flock to Bondi Beach for the traditional expats Christmas Day celebration in Sydney, Australia, 25 December 2014. Expats of all nationalities have been flocking to Bondi Beach for Christmas Day for many years. (Photo by Dean Lewins/EPA)

Wildlife category, open shortlist. “Buffaloes and stars”. This picture, taken at Zimanga game reserve in KwaZulu-Natal, South Africa, used an in-camera multiple exposure, with the first lit for the buffaloes and the second focused on the stars. (Photo and caption by Andreas Hemb/2017 Sony World Photography Awards)

A man dressed as Darth Vader goes through the turnstile at Lermontovsky Prospekt station on the Moscow metro in Moscow, Russia on May 4, 2017. (Photo by Vyacheslav Prokofyev/TASS)

For centuries the Highlands peoples of Papua New Guinea fought over land, women and pigs. Sorcery and battle skills could elevate a clan to Bigmanship, where the bigger the “presentation”, the bigger the man. Clans therefore would paint their bodies and create fearsome masks as part of their psy. Here: These are the terrifying tribe of “mudmen” from a remote part of Papua New Guinea. (Photo by Jeremy Hunter/Exclusivepix Media)

A model wears a floral headdress at the Royal Horticultural Society's Chelsea Flower show in London, Britain, May 22, 2017. The prestigious Chelsea Flower Show, held annually since 1913 in the Royal Hospital Chelsea grounds, is open to the public from the 23rd to the 27th of May, 2017. (Photo by Dylan Martinez/Reuters)

A man sits waiting for a train on the London Underground in 1890, when the platform floors were still made from wooden floorboards. (Photo by Hi-Story/Alamy Stock Photo)