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)

Wakodahatchee wetlands, Delray Beach, Florida, US. Equipped with sinewy necks and spear-like bills, great blue herons can lunge with fearsome speed to strike their aquatic prey. Adults will also employ rapid stabbing motions as one aspect of their complex courtship displays; they’re seemingly dangerous moves, but fitting to the intensity of mating season. (Photo by Melissa Rowell/Audubon Photography Awards)

Decaying fishing trawlers known collectively as The Fleetwood Wrecks, are seen at low tide on the banks of the River Wyre in Fleetwood, Britain on September 26, 2023. (Photo by Lee Smith/Reuters)

Tao Xiangli gets out of his homemade submarine after operating it in a lake on the outskirts of Beijing September 3, 2009. Amateur inventor Tao, 34, made a fully functional submarine, which has a periscope, depth control tanks, electric motors, manometer, and two propellers, from old oil barrels and tools which he bought at a second-hand market. He took 2 years to invent and test the submarine which costs 30,000 yuan ($4,385). (Photo by Christina Hu/Reuters)

A model presents a creation at the Lingerie Show-Forum 2016 international lingerie, swimwear, homewear and hosiery trade show in Moscow, Russia, February 24, 2016. (Photo by Sergei Karpukhin/Reuters)

2016 Rio Olympics, Swimming, Preliminary, Men's 100m Backstroke, Heats, Olympic Aquatics Stadium, Rio de Janeiro, Brazil on August 7 2016. Christopher Reid (RSA) of South Africa competes. (Photo by Dominic Ebenbichler/Reuters)

Kieran Woolley of Australia crashes into a cameraman during mens park skateboard at the Olympics at Ariake Urban Park, Tokyo, Japan on August 5, 2021. (Photo by Lisi Niesner/Reuters)

A woman carries a heart shaped balloon while sitting with her husband on a motorbike during Valentine's day, in Karachi on February 14, 2021. (Photo by Rizwan Tabassum/AFP Photo)