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)

Chris Hondros, a Getty Images photographer, was fatally wounded on April 20, 2011, in a mortar attack by government forces while covering the civil war in Libya. Hondros' work is woven in our history as he covered everything from politics to marathons. A new film will focus on his life as told through his images. Here's a look at some of his finest and final work. Some of these images are graphic in nature

You might think Ysabel LeMay’s works are hyper-realistic paintings but they’re created through an innovative technique called photo fusion. The Quebec-born, U.S.-based artist takes hundreds of photographs for each piece, attunes the light and visual properties, then assembles one detail at a time in a painterly fashion to form a single composition. Each work takes 4 to 8 weeks on average.

Underwater photographer Sarah Lee uses a technique known as “duck diving” to capture these stunning photos of surfers in Hawaii. Surfers “duck dive” under the water to avoid incoming waves so they can get further out to sea. Photo: A surfer comes free from her surfboard. (Photo by Sarah Lee/Caters News)

Kim Leuenberger is a Swiss photographer with a love for travel. She believes we are all explorers and is currently studying photography at University of the Arts London. These photos are from her series, “Traveling Cars Adventures”. Photo: “Lover of the Light”, Red Union Jack Mini Cooper, Bern, Switzerland, October 2012. (Photo by Kim Leuenberger)

“Rivers Forgotten” is a journey through the passages and portals of the underground waterways that lie unseen below cities. Self-taught photographer Jeremy Kai brings these forgotten landscapes to light. Photo: Beneath the Toronto area, 2011. (Photo by Jeremy Kai)

“Photocillin is the pseudonym of Dr Andy Teo, physician and people photographer based in the Surrey/Hampshire borders near London in the UK. My style is about showing the beauty of people and the world in which they live in a retro-utopian way”. – Andy Teo. Photo: “Walking six feet tall”. (Photo by Photocillin)

Andre Ermolaev is a photographer from Moscow, Russia (featured previously). In an ongoing series of aerial photos, Andre captures Iceland’s incredible landscape like you’ve never seen. Many of his images focus on capturing glacial rivers flowing through Iceland’s volcanic areas and the patterns and colours that emerge from the resulting flow.