St Andrews University students skinny dip in the sea as May Day celebrations in St Andrews, Scotland on April 30, 2017. Hundreds of revellers ditched their clothes and bravely jumped into the bitterly cold North Sea. (Photo by Alamy Stock Photos)

Fans bath in the mud during the “Woodstock Festival Poland” on August 3, 2017 in Kostrzyn Nad Odra, Poland. The annual 3 day music festival organised by The Great Orchestra of Christmas Charity, one of Polands most respected charities aims at spreading awareness about drugs and violence. Przystanek Woodstock in Poland is the largest Europe open air festival. (Photo by Music/Alamy Stock Photo)

Women Wrestlers, Bolivia. Lucha libre (Bolivian wrestling) is one of the most popular sports in the country. Women wrestlers are known as cholitas and have in the last ten years become popular in the sport. Here, Carmen Rosa and Yulia la Pacena perform in a benefit show to raise money for the bathrooms of a school in La Paz, Bolivia, 26 June 2011. (Photo by Daniele Tamagni)

The Enemy, 1944. With the outbreak of world war two, photojournalism was enlisted in defence of Mother Russia. In this photo by Anatoli Egorov, who was wounded in action, corporal Stepan Vasiljevich Ovcharenko shoots at enemy troops with a machine gun. (Photo by Anatoli Egorov/Lumiere Brothers Center for Photography)

“Sniff out the Appenzell Cheese”. Alexander Hunter, 30, of Greenwich, Conn., took this photo in Appenzell, Switzerland, in September 2014. (Photo by Alexander Hunter)

An innovative artist has camouflaged nude bodies by painting them into the worlds most expensive artworks. New York body artist, Trina Merry picked the 20 top dearest paintings, then photographed naked models disguised as part of the piece. Here: Titled 8,100,000 after the price paid for Bal du moulin de la Galette. (Photo by Trina Merry/Caters News)

An ancient oak tree sits in a Shropshire field as the first signs of Spring begin to show across the United Kingdom on February 19, 2014 in Bridgnorth, England. (Photo by Christopher Furlong/Getty Images)