Mud-covered tourists pretend to be trapped inside a mud prison at the Daecheon Beach Mud Plaza in the city of Boryeong on South Korea's west coast, July 17, as they take part in the Boryeong Mud Festival, which opened that day and runs through July 26. Boryeong mud is rich in natural mineral component and is considered to prevent skin aging. (Photo by EPA/Yonhap)

A diesel locomotive has ended up in the river Venoge on March 8, 2013 near Penthalaz, Western Switzerland. The freight locomotive derailed near Cossonez railway station with its driver slightly injured. (Photo by Fabrice Coffrini/AFP Photo)

In this photo provided by Mickey Nuttall, members of an international team of skydivers join hands, flying head-down to build their world record skydiving formation, Friday, July 31, 2015, over Ottawa, Ill. (Photo by Jason Peters via AP Photo)

A woman rides a donkey during a donkey race in Roum village, Jizeen countryside, southern Lebanon, August 9, 2015. (Photo by Ali Hashisho/Reuters)

A soldier poses with a Hythe Mk III Gun Camera during training activities at Ellington Field, Houston, Texas in April of 1918. The Mk III, built to match the size, handling, and weight of a Lewis Gun, was used to train aerial gunners, recording a photograph when the trigger was pulled, for later review, when an instructor could coach trainees on better aiming strategies. (Photo by Harry Kidd/WWI Army Signal Corps Photograph Collection via The Atlantic)

Two traditional folk dancers performing in Teheran, Iran. (Photo by Keystone Features/Getty Images). 25th January 1961

Attnedees dressed in Zombie outfits walk down the Gaslamp Quarter outside of the 2015 Comic-Con International in San Diego, California July 8, 2015. (Photo by Sandy Huffaker/Reuters)

This photo provided by Joan Marcus on August 28, 2015 shows ballerina Misty Copeland in the musical “On the Town” at the Lyric Theatre in New York. Until September 6, 2015 Copeland will play Miss Turnstiles, a love interest for one of three sailors enjoying a few hours of shore leave in 1940s New York. (Photo by Joan Marcus via AP Photo)