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)

Heavy artillery on parade during a review of the Moscow Garrison troops during the May Day celebrations in Red Square, passing posters of Lenin and Stalin. (Photo by N. Sitnikov/Hulton Archive/Getty Images). 1st May 1947

A man pours water on his camel on a hot summer day in Ahmedabad, India, May 18, 2017. (Photo by Amit Dave/Reuters)

A mahout bathes his elephant in the river Sabarmati on a hot summer day in Ahmedabad, India May 21, 2017. (Photo by Amit Dave/Reuters)

A makeup artist works on a model during the Tunis Fashion Week 2018 in Tunis, Tunisia, 12 May 2018. (Photo by Mohamed Messara/EPA/EFE)

Michelle Rodriguez attends the De Grisogono Party during the 71st annual Cannes Film Festival at on May 15, 2018 in Antibes, France. (Photo by INSTARimages.com)