Visitors crowd an artificial wave swimming pool at a tourist resort to escape the summer heat in Daying county of Suining, Sichuan province, China, July 11, 2015. (Photo by Reuters/Stringer)

Models prepare backstage before a presentation as part of Fashion Weekend Plus Size Summer 2015 collection show in Sao Paulo, July 25, 2015. (Photo by Nacho Doce/Reuters)

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)

Models present creations for Etam during the 2017 Spring/Summer ready-to-wear collection fashion show, on September 27, 2016 in Paris, France. (Photo by Swan Gallet/WWD/Rex Features/Shutterstock)

Models dance during the presentation of Stella McCartney's Spring-Summer 2017 ready-to-wear fashion collection presented Monday, October 3, 2016 in Paris. (Photo by Francois Mori/AP Photo)

A model wears a creation for Miu Miu's Spring-Summer 2017 ready-to-wear fashion collection presented Wednesday, October 5, 2016 in Paris. (Photo by Francois Mori/AP Photo)

A woman carries earthen pots to fill them with drinking water on a hot summer day, on the outskirts of Ajmer, Rajasthan, India April 25, 2017. (Photo by Himanshu Sharma/Reuters)

A model poses prior the Etam show as part of the Paris Fashion Week Womenswear Spring/Summer 2018 on September 26, 2017 in Paris, France. (Photo by Vittorio Zunino Celotto/Getty Images)