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)

Students stand on the roof of a wooden boat as haze blankets the Musi River while they travel to school in Palembang, on Indonesia's Sumatra island, September 10, 2015. Indonesia is investigating 10 firms over worsening forest fires that have created a blanket of smog over Southeast Asia, threatening them with sanctions if they are found responsible, a government minister said on Tuesday. The thick haze from Indonesia's Sumatra and Kalimantan islands has forced the repeated cancellation of flights in the area and pushed air quality to unhealthy levels in neighbouring Singapore and Malaysia. (Photo by Reuters/Beawiharta)

Girls take a selfie at the haze shrouded Batanghari River bridge in Jambi, Indonesia Sumatra island, September 14, 2015. Indonesian islands are blanketed in the so-called “haze”, caused by slash-and-burn clearances on the islands of Sumatra and Borneo, which makes thousands sick, delays flights and pushes air quality to unhealthy levels in neighboring Singapore and Malaysia. (Photo by Reuters/Beawiharta)

Rowers enter in Canaregio river during the 42nd Venice Vogalonga on May 15, 2016 in Venice, Italy. 42 years ago a group of Venetians, both amateur and professional rowers, came up with an idea of non-competitive race in which any kind of rowing boat can take part. The first Vogalonga began with the message to protest against the growing use of powerboats in Venice and the swell damage they do to the historic city. (Photo by Awakening/Getty Images)

Long-tailed mayflies (Palingenia longicauda) mate on the surface of the Tisza river near Tiszakurt, Hungary, June 14, 2016. Millions of these short-lived mayflies engage in a frantic rush to mate and reproduce before they perish in just a few hours during “Tiszaviragzas” or Tisza blooming season from late spring to early summer every year. (Photo by Laszlo Balogh/Reuters)

The three orangutans at Pairi Daiza zoo, Belgium, developed a “special bond” with the otters after their river was run through the ape enclosure on March 2020. The zoo said it enriched both species’ environments. An animal – and this is even more the case of orangutans, with whom humans share 97 per cent of their DNA – must be entertained, occupied, challenged and kept busy mentally, emotionally and physically at all times. (Photo by Pascale Jones/The Sun)

People in ethnic costumes jump over a bonfire during Ivan Kupala Day celebrations held by the Pripyat River in the town of Turauin Gomel Region, Belarus on July 6, 2020. Ivan Kupala Day, also known as Ivana-Kupala or Kupala Night, is a traditional pagan holiday celebrated in eastern Slavic cultures. Various rituals are traditionally performed on Kupala Night, including making flower wreaths, fortune-telling, jumping over bonfires, and burning a wheel-like effigy symbolizing the sun. (Photo by Natalia Fedosenko/TASS)

A woman poses by “Leaf Spirit” by Simon Gudgeon at the FORM 24 show at Sculpture by the Lakes, on April 02, 2024 in Dorchester, England. The award-winning sculpture show runs from April 2 to June 1, with works by more than 35 leading contemporary sculptors exhibited throughout 26-acres of lakes, rivers, gardens, and woodlands as well as in the Gallery and The Retreat. FORM includes a series of talks and events to accompany the exhibition, including “Meet the Artist” Q&A sessions with exhibiting sculptors, workshops and demonstrations. (Photo by Finnbarr Webster/Getty Images)