In this November 30, 2017 photo, Douglas scoops up mud from the bottom of the polluted Guaire River, in search of gold and anything valuable he can sell, in Caracas, Venezuela. Some stretches of the river smell of sewer while others emit a toxic odor of fuel, a stench that stays in ones nose for hours after leaving the water. (Photo by Ariana Cubillos/AP Photo)

A man transports the carcass of a car on a two- wheeled carriage in a neighborhood in Abobo, a suburb of Abidjan, Côte d’Ivoire on December 1, 2017. (Photo by Issouf Sanogo/AFP Photo)

(L-R) Chris Diamantopoulos, AnnaLynne McCord, Matt Jones and Jane Seymour visit the Build Series at Build Studio on January 23, 2018 in New York City, United States. (Photo by Brad Barket/Getty Images)

A tourist clad in Japanese kimono takes a picture in front of s portrait shop in Tokyo's Asakusa district, Thursday, February 15, 2018. Asakusa is a popular district four tourists in the capital. (Photo by Shizuo Kambayashi/AP Photo)

Racegoers during Ladies Day of the 2018 Cheltenham Festival in Cheltenham, England on March 14, 2018. (Photo by Graham Stone/Rex Features/Shutterstock)

An Afghan boy jumps off the turret of a Soviet tank on a hilltop on the the outskirts of Kabul, Sunday, March, 4, 2018. (Photo by Rahmat Gul/AP Photo)

An ethnic Lisu man dances barefoot on hot charcoal embers to celebrate the annual Knife Pole Festival in Luzhang township of Nujiang Lisu Autonomous Prefecture in Yunnan province, China, March 29, 2018. (Photo by Aly Song/Reuters)

In this photo taken Friday, September 4, 2015, tourists Sarah and John Scott from Worcester, England, take a step back as a male silverback mountain gorilla from the family of mountain gorillas named Amahoro, which means “peace” in the Rwandan language, unexpectedly steps out from the bush to cross their path in the dense forest on the slopes of Mount Bisoke volcano in Volcanoes National Park, northern Rwanda. Deep in Rwanda's steep-sloped forest, increasing numbers of tourists are heading to see the mountain gorillas, a subspecies whose total population is an estimated 900 and who also live in neighboring Uganda and Congo, fueling an industry seen as key to the welfare of the critically endangered species as well as Rwanda's economy. (Photo by Ben Curtis/AP Photo)