Smithsonian National Zoo biologist Leigh Pitsko releases a male lion cub for its swim test in the zoo habitat moat, in Washington May 6, 2014. Four, unnamed ten-week old lion cubs were tested today for their ability to swim and remove themselves from their zoo habitat moat. (Photo by Gary Cameron/Reuters)

Competitors take part in the Red Bull Crashed Ice Cross Downhill World Championship in Marseille, France, January 14, 2017. (Photo by Jean-Paul Pelissier/Reuters)

Max Niedermaier of Germany collides with uncontrolled motorcycle of Niclas Svensson of Sweden during Astana Expo FIM Ice Speedway Gladiators World Championship at the Medeo rink in Almaty, Kazakhstan, February 18, 2017. (Photo by Shamil Zhumatov/Reuters)

A model walks the runway at the Dolores Cortes swim show during Mercedes-Benz Fashion Week Swim 2012 at The Raleigh on July 16, 2011 in Miami Beach, Florida. (Photo by Frazer Harrison/Getty Images for Dolores Cortes)

Event curators Harry Parr (L) and Sam Bompas (R) sit in paddle boats in the Truvia Voyage of Discovery installation on the roof of Selfridges department shop on July 21, 2011 in London, England. Selfridges is opening its roof to the public for only the second time since WW2 to host the installation, which includes a boating lake with dyed water and bar. (Photo by Matthew Lloyd/Getty Images)

Visitors view ice sculptures at the 29th Harbin International Ice and Snow Festival on January 5, 2013. (Photo by Associated Press)

Newly-wed couples attend their group wedding ceremony which was held as part of the Harbin International Ice and Snow Festival in the northern city of Harbin, Heilongjiang province January 6, 2016. As many as 15 couples attend this mass wedding ceremony. (Photo by Aly Song/Reuters)