Cassie Douthwaite (L) and Stuart Abercrombie from Preston pose for a portrait in Brighton, southern England February 16, 2013. Brighton hosts “The Brighton Tattoo Convention” this weekend, an annual two-day gathering which attracts visitors, performers and tattoo artists from around the world. Photograph taken February 16, 2013. (Photo by Toby Melville/Reuters)

In this March 14, 2015 photo, tourists take pictures from a viewing area at Iguazu Falls in Brazil. From walkways and bridges, viewers can count 270 water falls almost 100 meters (330 feet) high. (Photo by Jorge Saenz/AP Photo)

A devotee takes a holy bath at the Balaju Baise Dhara (22 water spouts) during the Baishak Asnan festival in Kathmandu April 4, 2015. Devotees believe that the water from these stone spouts, which is collected from the catchment area of the Nagarjun forest behind the spouts, will cure pains and skin diseases. (Photo by Navesh Chitrakar/Reuters)

Sophie and Sarah, old English sheepdogs, watch the sea from their plastic chairs. Amateur photographer Cees Bol, from the Netherlands, documents the lives of his beloved pooches Sophie and Sarah by taking pictures of them every day. (Photo by Cees Bol/Caters News Agency/Mercury Press)

“One in Eight Hundred” by Mario Wezel, from Germany, is the winner of the “People” category. The title refers to the odds given to Martin and Karina at their prenatal screening before their daughter, Emmy, was born. The five-year-old from Denmark has Down's Syndrome. (Photo by Mario Wezel/Sony World Photography Awards)

“Winter Climbing from inside Ben Nevis”. The view from inside the mountain, as a winter climber passes through the cave on Minus Three gully. Photo location: Ben Nevis, Fort William, Scotland. (Photo and caption by Daniel Wildey/National Geographic Photo Contest)

Athletes in action during the international parachuting competition Mountain Gravity in Quinto, Switzerland, 27 August 2015. Some 200 participants from all over the world are expected to jump at the event running from 22 to 30 August 2015. (Photo by Samuel Golay/EPA)

This image obtained January 31, 2017 from the US Geological Survey's Hawaiian Volcano Observatory showing a lava stream, pouring out of the lava tube on the sea cliff at the Kamokuna ocean entry from the Kilauea Volcano on January 29. (Photo by AFP Photo/USGS)