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 Christian pilgrim is baptised by a priest in the muddy water of the Jordan River at the Kasser-Al-Yahud baptismal site near the West Bank city of Jericho, on April 11, 2017. According to the gospels Jesus Christ was baptised in the waters of the Jordan River by John the Baptist. (Photo by Gali Tibbon/AFP Photo)

A girl watches as Saen Dao, an eight-year-old female asian elephant, and her mahout perform underwater during a show at the Khao Kheow Open Zoo in Chonburi south of Bangkok on June 1, 2017. (Photo by Roberto Schmidt/AFP Photo)

A baby Sumatran orangutan is bathed after arriving at a wildlife center at Ratchaburi province in Thailand September 13, 2017. (Photo by Kerek Wongsa/Reuters)

Tourists feed freshly picked grapes to 40-year-old elephant Boonruen, a long-term resident of the Hua Hin Hills vineyard, that used to be an elephant corral in Hua Hin, about 200km southwest of Bangkok, Thailand, 08 March 2016. The winery is among a handful of companies producing new latitude wines in non-traditional wine areas of the world near the equator. Harvest is only once a year in Thailand, this year in March. (Photo by Barbara Walton/EPA)

Revellers kiss under a rainbow flag during the Gay Pride parade along Paulista Avenue in Sao Paulo, Brazil on June 3, 2018. (Photo by Nacho Doce/Reuters)

Opossums on their mothers back at a game reserve in Central Minnesota, USA, on September 2, 2013. (Photo by Caters News Agency)

Former NBA player Yao Ming (R), a member of the 12th Chinese People's Political Consultative Conference (CPPCC) National Committee, is seen during an interview in Beijing, China, in this picture taken March 9, 2016. (Photo by Reuters/China Daily)