The adventurous explorers have snapped themselves in shark-infested waters, at the side of an active volcano, atop a Hong Kong skyscraper surrounded by toxic smog, and even perched on the top of iconic Rio statue of Christ the Redeemer. Here: Ervin Punkar using a selfie stick to take a photo from the very top of the 600ft TV tower in Tartu, Estonia. (Photo by Ervin Punkar/Caters News Agency)

Each year Nikon Small World recognizes the excellence of photography taken under the microscope. The contest showcases the beauty and complexity of life. Anyone interested in microscopy and photography can enter the contest and in its 42nd year, Nikon Small World received 2,000 entries from 70 countries. Here: 11th Place; Scales of a butterfly wing underside (Vanessa atalanta). (Photo by Francis Sneyers/Nikon's Small World 2016)

Meet the world's smoothest cuddliest hedgehog. Names after brave hero, but Nelson is completely bald so when curled up he looks like an egg. Doesn't have a single prickle or strand of hair. Thought to be suffering a stress related alopecia following a trauma in the wild. Volunteers have been massaging him for half an hour a day for the last year to encourage spikes to grow. Now given up but he still gets daily massages because he enjoys them so much and to keep his cuddle skin soft and smooth. Unlike his namesake Nelson could not defend himself so will live out his days at the Foxy Lodge Wildlife Rescue in Hemsby, England. (Photo by Jeremy Durkin)

In this undated photo provided by LittleFriendsPhoto.com via Six Flags Discovery Kingdom, Kai, a 17-year-old male California sea lion at Six Flags Discovery Kingdom in Valejo, Calif. peers into the lens of photographer Seth Casteel, known for his “Underwater Dogs” photo series. ... (Photo by Seth Casteel/AP Photo/LittleFriendsPhoto.com via Six Flags Discovery Kingdom)

“For centuries, the Moken sea nomads have traveled the islands between Thailand and Myanmar fishing and foraging for food on the sea floor. Throughout the Mergui Archipelago, Moken migrate in flotillas of Kabangs (traditional boat of the Moken people), stopping at different islands and beaches. Expert freedivers, the Moken have adapted physically to an aquatic life, developing unique characteristics that let them see better and hold their breath longer while underwater”. – Taylor Weidman. Photo: Hook, an indigenous Moken man, holds a three-pronged throwing spear and searches for fish in the waters of Ko Surin National Park. March 1, 2013 – Ko Surin, Thailand. (Photo by Taylor Weidman/zReportage via ZUMA Press)

Trees in a park are illuminated with a red light as a part of an art project in Timmendorfer Strand, northern Germany Wednesday, October 26, 2016. (Photo by Michael Probst/AP Photo)

In this picture taken on December 13, 2017, a woman commutes on a street on a cold day in Baoding. As temperatures dipped below freezing in a northern Chinese village, a group of parka-clad women tried to stay warm as they played mahjong around a small gas stove in a grocery store. (Photo by Fred Dufour/AFP Photo)

Two female holidaymakers relax on an unidentified beach of England, September 21, 1940, as a soldier, eyes straight ahead, stands guard at a barrier built as a defense against possible invasion by Germany. (Photo by AP Photo)