People wear costumes as they participate in the ancient Yule Log dragging tradition during winter solstice celebrations in Riga, Latvia, December 21, 2015. (Photo by Ints Kalnins/Reuters)

People inspect hookahs shaped like rifles on display for sale in a souk at the port city of Sidon, southern Lebanon, December 23, 2015. (Photo by Ali Hashisho/Reuters)

People dressed as Father Frost, the equivalent of Santa Claus, and Snow Maiden take part in the contest “Yolka-fest-2014” (Fir-festival-2014) in Minsk December 12, 2014. (Photo by Vasily Fedosenko/Reuters)

People look at huge waves crashing on the San Esteban de Pravia seafront, northern Spanish region of Asturias February 8, 2016. (Photo by Eloy Alonso/Reuters)

Krista Long began snapping pics of people sliding down a water slide after many visits to the local water park with her tween daughters. The result is an action-packed series that show emotions ranging, she says, “from pure joy to fear, in anticipation of the inevitable splash-down!” (Photo by Krista Long)

“Shortly after he arrived, Van Agtmael witnessed the aftermath of this suicide bombing at a cafe that soldiers frequented in Mosul. Nine people died and 23 were wounded”. (Photo and caption by Van Agtmael/Harrison Jacobs/Magnum Photos)

People walk down the street while Hurricane Matthew approaches in Port-au-Prince, Haiti October 3, 2016. (Photo by Carlos Garcia Rawlins/Reuters)

A female soldier from the honour guards prepares for a welcoming ceremony for Uruguay's President Tabare Vazquez at the Great Hall of the People in Beijing, China, October 18, 2016. (Photo by Jason Lee/Reuters)