Ukrainians swim in an ice hole as part of the celebration of the Epiphany in Kiev, Ukraine, Monday, January 19, 2015. Orthodox believers celebrate the holiday of the Epiphany on Jan. 19, and traditionally bathe in holes cut through thick ice on rivers and ponds to cleanse themselves with water deemed holy for the day. (Photo by Sergei Chuzavkov/AP Photo)

A competitor gestures as he crawls beneath barbed wire during the Tough Guy event in Perton, central England February 1, 2015. The annual event to raise cash for charity challenges thousands of international competitors in a cross country run followed by an assault course consisting of obstacles including water, fire and tunnels. (Photo by Phil Noble/Reuters)

Freshmen in Zhengzhou Institute of Aeronautical Industry Management head bottles of mineral water for upright stand during military training on September 17, 2015 in Zhengzhou, Henan Province of China. More than 6,800 freshmen in the school are required to take part in the military training. (Photo by ChinaFotoPress/ChinaFotoPress via Getty Images)

A Thai jockey competes during an annual water buffalo race in Chonburi Province, south of Bangkok, Thailand, Monday, October 26, 2015. The annual race is a celebration among rice farmers before harvest. (Photo by Sakchai Lalit/AP Photo)

Tourists pose for a selfie in Cancun, October 13, 2015. Cancun's transformation in the 1970s from a small Caribbean fishing village into a strip of nightclubs and high-rise hotels has reduced biodiversity and polluted water resources as infrastructure struggles to keep up. (Photo by Edgard Garrido/Reuters)

A local resident stumbles as he wades through flood water on a residential street in Carlisle, Britain December 6, 2015. British police have declared a major incident in northern England after prolonged heavy rain caused widespread flooding and forced emergency services to evacuate residents from their homes. (Photo by Phil Noble/Reuters)

Lenka Tanner is pictured in Nottingham, United Kingdom on March 11, 2015. She starred in the Kuoni advert, Run on Water, advertising luxury holidays. She has set up her own synchronised swimming team called AquaStars. Tanner was born in Slovakia and starting synchronised swimming at the age of six. (Photo by Lucy Ray/The Guardian)

A child looks at a polar bear swimming under a water in its enclosure on a hot summer day at Prague Zoo, Czech Republic, July 30, 2015. (Photo by David W. Cerny/Reuters)