A man pours mud water on the head of his girl friend during the Boryeong Mud Festival at Daecheon Beach in Boryeong, South Korea, Friday, July 18, 2014. The annual mud festival features mud wrestling and mud sliding. (Photo by Ahn Young-joon/AP Photo)

Partipants vie for the ball during the 11th Mud Olympics held at the North Sea coast in Brunsbuettel, Germany, July 11, 2015. Amateur athletes have competed in several disciplines at the Mud Olympics since 2004. (Photo by Axel Heimken/EPA)

Finding just the right spot above the clouds at Camp 1 on Ama Dablam, Danuru Sherpa uses his iPhone to catch up with friends and family. Even at 18,500 feet (5,654 meters), climbers here can check their email and other dispatches from the world below. (Photo by Aaron Huey/National Geographic)

Children watch their classmate pour cold water on herself under the watch of a fitness coach at a local kindergarten in Russia's Siberian city of Krasnoyarsk, March 11, 2015. The program, which also involves sports training and sauna usage, has been practiced by the kindergarten for more than 15 years as they believe it has health benefits and keeps the children fit. Children start pouring cold water on themselves outdoors after about three years of training and undergoing medical tests, and the kindergarten is the only one in the region that practices these exercises, according to employees. (Photo by Ilya Naymushin/Reuters)

Sydney Truba, 11, of Melvindale, Michigan lies in a giant lake of mud during Wayne County's 2011 Mud Day event at Nankin Mills Park July 12, 2011 in Westland, Michigan. The annual event consists of 20,000 gallons of water mixed with 200 tons of topsoil. (Photo by Bill Pugliano/Getty Images)

A Hindu holy man, or sadhu, smokes marijuana in a chillum at the premises of Pashupatinath Temple, ahead of the Shivaratri festival in Kathmandu, Nepal February 15, 2017. (Photo by Navesh Chitrakar/Reuters)

Tourists look at other festival-goers playing in the mud during the Boryeong Mud Festival at Daecheon beach in Boryeong, about 190 km (118 miles) southwest of Seoul, July 19, 2013. About 2 to 3 million domestic and international tourists visit the beach during the annual mud festival, according to the festival organisers. (Photo by Lee Jae-Won/Reuters)

Participants arrive at the finish line during the annual Maldon Mud Race in Maldon, east England on May 7, 2017. Originating in 1973, the race involves competitors racing around a course through the River Blackwater in Essex at low tide. (Photo by Daniel Leal-Olivas/AFP Photo)