A Tampa Bay Buccaneers cheerleader, wear a military-inspired outfit as part of the NFL's Salute to Service program, flips her hair during a game between the Buccaneers and San Diego Chargers in Tampa, on November 11, 2012. (Photo by Phelan M. Ebenhack/Associated Press)

Irwan bathes a domesticated crocodile at his house in Bogor, Indonesia on January 22, 2018. Irwan found it as a baby and now it has been living with Irwans family for 20 years. Indonesia is known as a hotbed of exotic pet domestication and trade. People have been known to keep endangered animals such as slow lorises, eagles and pangolins, angering conservationists and animal rights activists. (Photo by Eko Siswono Toyudho/Anadolu Agency/Getty Images)

The photography of Art Wolfe covers the globe, capturing landscapes, wildlife, and cultures from every continent; here he talks through a selection of his favourite images. Art Wolfe is an American photographer and conservationist. His photographs have been noted by environmental advocacy groups for their “stunning” visual impact. Here: Snowy owlets (Bubo scandiacus), Arctic National Wildlife Refuge, Alaska, USA. (Photo by Art Wolfe/Art Wolfe Stock)

International photographic competition, which runs in association with the Royal Botanic Gardens in Kew, London, awards special prize for the best close-up images. Here: Winner – Mayflies by Petar Sabol, Goričan, Croatia. (Photo by Sabol Petar/International Garden Photographer of the Year)

“Lofoten Glow”. I was desperately searching a good sunrise spot this particular morning. Normally Storvatnet Lake is completely covered in snow, so you can only imagine my surprise when I saw these crazy ice formations almost being shot out of the frozen lake. I put my crampons on and took a big risk walking out. I could hear the ice cracking underneath my feet, and when you’re all alone in a fjord/canyon like this – the cracks are echoed and sound really frightening. Was it worth it? I sure think so! Photo location: Storvatnet, Lofoten Islands in Northern Norway. (Photo and caption by Stian Klo/National Geographic Photo Contest)

Tanzania, 1964. A touching moment between primatologist and National Geographic grantee Jane Goodall and young chimpanzee Flint at Tanzania's Gombe Stream Reserve. (Photo by Hugo van Lawick via National Geographic)

This restroom on the rubbly flanks of Jonsknuten in Norway looks up at the peak of the 904m mountain. Yu have to leave the door open to enjoy the view but the chances of being disturbed are minimal. (Photo by Olaf Menz/Lonely Planet)

Beneath the Swedish capital lies an intricate web of underground train lines. More than 90 of the 100 stations in the 110km tunnel system, sometimes referred to as “the world’s longest art gallery”, have been decorated with paintings, installations, mosaics and sculptures by 150 artists since the 1950s. After spending a couple of weeks exploring arctic Norway and Sweden, London-based travel photographer Conor MacNeill headed underground to capture images of the metro stations. Here: A rainbow arcs over a girl on the platform of Stadion station. (Photo by Conor MacNeill/The Observer)