A competitor participates in the Tough Mudder challenge near Henley-on-Thames in southern England May 2, 2015. (Photo by Eddie Keogh/Reuters)

A helicopter drops water over a wildfire as a firefighter works to contain it in Benahavis, southern Spain, May 19, 2015. (Photo by Jon Nazca/Reuters)

Hungarian wrestlers fight during the Hungarian wrestling Championship in Budapest November 29, 2014. (Photo by Laszlo Balogh/Reuters)

Women loyal to the Houthi movement parade to show support to the movement in Sanaa, Yemen January 17, 2017. (Photo by Khaled Abdullah/Reuters)

Steam emerges from a cooling tower of the nuclear power plant Leibstadt near Leibstadt, Switzerland, November 18, 2014. (Photo by Arnd Wiegmann/Reuters)

A devotee smiles as she offers prayers during the Swasthani Brata Katha festival in Kathmandu, Nepal January 12, 2017. (Photo by Navesh Chitrakar/Reuters)

Waves hit the seawall during heavy seas and high winds in Dawlish in south west Britain, February 2, 2017. (Photo by Toby Melville/Reuters)

A mahout cleans the dust from his elephant in Ahmedabad, India, February 8, 2017. (Photo by Amit Dave/Reuters)