The fourth annual BigPicture Natural World Photography Competition aims to celebrate the diversity of life on Earth, and encourages people to protect and conserve it. Here: “The Salmon Catchers”. Terrestrial Wildlife. To capture this view of a mother grizzly bear and her cub, photographer Peter Mather set up a camera trap on a log that he knew the bears tended to traverse while fishing for salmon, in the Yukon River watershed in Canada. (Photo by Peter Mather/BigPicture Natural World Photography Competition 2017)

Sandrine Kerfante has had a fascination with “doubles” ever since meeting her mother’s twin as a child. In 2012, this lifelong captivation inspired her to create a blog called twin-niwt, which celebrates photographs of doubles in all their forms. “I’m fascinated by the idea of the duo, repetition, symmetry, reflection, mirror games and all the symbolism associated with it”, she says. “I think it’s a topic often present in photography, more or less consciously”. (Photo by Sandrine Kerfante/The Guardian)

The ferocity of crises worldwide is forcing a record number of people to flee their homes, seeking some form of safety within their own country or across international borders. There are 65.3 million displaced people worldwide, including 21.3 million refugees. Most have lost their homes to armed conflict or natural disasters but other factors, such as extreme poverty and climate change, also drive displacement. The International Organisation for Migration commissioned photojournalist Muse Mohammed to document the plight of the displaced. (Photo by Muse Mohammed/IOM)

These breath-taking photographs reveal the everyday lives of animals living in the wild. The incredible images were taken by wildlife photographer Wim van dan Heever, from Pretoria, South Africa, during trips to locations including Japan, Botswana and Svalbard. The 43-year-old has been photographing wildlife since he was a young boy and turned his passion for animals into a career and set up ODP Safaris. He has travelled across the globe to photograph wild animals – from lions and tigers, to elephants, dolphins and eagles – as they hunt, give birth and graze in their natural habitats. Here: Lions submerged in water. (Photo by Wim van den Heever/Caters News)

Daniel Fox inside the Mendenhall Glacier, in September 2014, in Juneau, Alaska. Driving in an open-roofed jeep is no longer the fashionable way to see wildlife – as this adventurer shows. A keen wildlife photographer has circled islands in the south of Alaska, the United States, in a kayak to see spectacular scenery and animals. Daniel Fox, 40, from San Francisco spent three months travelling around the islands by kayak, meeting sea lions and brown bears along the way. (Photo by Daniel Fox/Barcroft Media)

A selection of work by four photojournalists who have won grants of $10,000 and editorial support from the agency. Here: “Chasing Winter” by Katie Orlinksy. In late summer and early autumn polar bears flock to the native village of Kaktovik in the Alaskan Arctic to eat at “the boneyard” – the remains of whales annually hunted by the community. (Photo by Katie Orlinsky/Getty Images)

Vladimir Putin shows a hold to a young judo wrestler at the Regional Judo Center at the Arena Sports Complex in the Siberian city of Kemerovo on January 24, 2012, during his visit to the region. Putin is known for his passion for judo, in which he has a black belt. (Photo by AFP Photo/STR)

The First U.S. Spacewalk – Gemini 4 Ed White made the United States' first spacewalk on June 3, 1965 during the Gemini 4 mission. The extra-vehicular activity (EVA) started at 19:45 UT (3:45 p.m. EDT) on the third orbit when White opened his hatch and used the hand-held manuevering oxygen-jet gun to push himself out of the capsule. (Photo by NASA)