Pope Francis greets the crowd from his popemobile in downtown Rio de Janeiro. Pope Francis touched down in Rio de Janeiro on Monday, starting his first foreign trip as pontiff and a weeklong series of events expected to attract more than a million people to a gathering of young faithful in Brazil, home to the world's largest Roman Catholic population. (Photo by Ueslei Marcelino/Reuters)

In 2002 photographer Corey Arnold left behind a poor economy in San Francisco and headed up to Alaska to try his luck at his longtime passion of fishing. Arnold, who had worked summers during college on a salmon boat in Alaska, signed onto the f/v Rollo, a crabbing boat that fishes in the dangerous Bering Sea. While working long, strenuous hours on the Rollo, Arnold often stole away with the captain’s permission to grab his camera and photograph the crew and the ship. Arnold eventually put together “Fish Work: Bering Sea”, a documentation of his seven adventurous and dicey crab seasons aboard the Rollo. (Photo by Corey Arnold)

A view of an installation as part of the “S.A.C.R.E.D” exhibition by Chinese artist Ai Weiwei during the 55th La Biennale of Venice, in the church of Sant'Antonin in Venice May 28, 2013. (Photo by Stefano Rellandini/Reuters)

A street in the Cuban capital, Havana, is home to 12 sets of twins, ranging from toddlers to senior citizens. Some say it could be something in the water. Others point to a tree with mystical significance for locals. And maybe it's just chance. Photo: In this September 29, 2013 photo, nine-year-old twin sisters Camila, left, and Carla Rodriguez pose for a portrait along their street in Havana, Cuba. 12 sets of twins live along two consecutive blocks in western Havana, ranging in age from newborns to senior citizens. “We love living on this block because we have twin friends”, said Carla. (Photo by Ramon Espinosa/AP Photo)

A child plays with a soap bubble on the city hall plaza on March 14, 2015 in Paris. (Photo by Dominique Faget/AFP Photo)

A cloud of black smoke billows out the exhaust pipe of John Robertson's diesel dragster as he runs down the track during the 2015 NHRA Kansas Nationals, Friday, May 22, 2015, at Heartland Park in Topeka, Kan. (Photo by Chris Neal/The Topeka Capital-Journal via AP Photo)

Men hang at the back of a truck loaded with farm produce along a road in Ikeja district in the commercial capital Lagos, Nigeria December 19, 2016. (Photo by Akintunde Akinleye/Reuters)

A Hindu devotee is helped by other people as she walks on burning coals during a religious procession Vel Festival of the Hindu goddess Maha Mariamman (Sheetla Mata), in New Delhi, India, 06 April 2017. People get their bodies pierced with different kinds of metal needles and rods and participate in a religious procession as thanks giving gesture to the goddess in return of their fulfilled wishes during the annual procession. (Photo by Rajat Gupta/EPA)