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)

A girl walks along former railway tracks in the so- called “Tunnel of Love”, surrounded by arches of intertwined trees, near the Ukrainian village of Klevan, Rivno region, on August 6, 2018. The tunnel of about five kilometres in length is a botanical phenomenon, which became a cult place for tourists and couples in love. The tourist legend says that wishes of couples in love will come true, if the couple passes through the tunnel. (Photo by Sergei Supinsky/AFP Photo)

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)

Heimana Reynolds of USA in action during a training session prior to the World Skate Park World Championships at the Parque Candido Portin​ari in Sao Paulo, Brazil, 11 September 2019. (Photo by Sebastião Moreira/EPA/EFE)

A tattooist works on a tattoo with oriental designs in the course the International Tattoo Convention on October 25, 2019 in Amsterdam, Netherlands. Today begins the 15th edition of the Amsterdam International Tattoo Convention. During the weekend tattooers from all over the world will show their new designs with which they will compete in a contest that includes all styles and categories. (Photo by Nacho Calonge/Getty Images)

The sky looked on fire this morning, as it made the clouds glow red, just before sunrise at Peterborough Rowing Lake, in Nene Park, UK on January 18, 2017. (Photo by Paul Marriott/Rex Features/Shutterstock)

A hot air balloon competition called “Grudziadzkie Zawody Balonowe” is held in Lisie Katy, central-northern Poland, 14 May 2021. The compe​tition is held for the eighteenth time. (Photo by Tytus Zmijewski/EPA/EFE)

People are silhouetted while riding the Atmosfear double swing, which lifts riders more than 66 meters into the air while spinning at up to 70 km/h, at the Pacific National Exhibition at sunset in Vancouver, British Columbia, on Tuesday, August 31, 2021. (Photo by Darryl Dyck/The Canadian Press via AP Photo)