Alex Mustard / A diver explores Silfra Canyon, a deep fault filled with fresh water in the rift valley between the Eurasian and American tectonic plates at Thingvellir National Park, Iceland. May 2011. In this phot...

Danny Green / Polar bear (Ursus maritimus) walking across sea ice, reflected in water. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) female resting with cubs on glacier. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs, standing on sea ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs resting on sea ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) female and cubs, one cub walking up slope of ice in foreground. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) and cubs feeding on Whale carcass, on iceberg. Svalbard, Norway, July 2018.

Danny Green / Polar bear (Ursus maritimus) standing on ice. Svalbard, Norway, July.

Danny Green / Polar bear (Ursus maritimus) male standing beside rocks in frozen and snow covered landscape. Svalbard, Norway, April 2019.

Danny Green / RF - Arctic fox (Alopex lagopus) in winter pelage, camouflaged in snow. Svalbard, Norway, April (This image may be licensed either as rights managed or royalty free.)

Danny Green / RF - Reindeer (Rangifer tarandus) walking up slope in snow. Svalbard, Norway, April. (This image may be licensed either as rights managed or royalty free.)

Danny Green / Reindeer (Rangifer tarandus) hunkering down in snow during blizzard. Svalbard, Norway, April.

Danny Green / Polar bear (Ursus maritimus) sleeping in snow. Churchill, Manitoba, Canada, November.

Nick Garbutt / American bison (Bison bison) female covered in hoar frost near hot spring, portrait. Midway Geyser Basin, Yellowstone National Park, USA. February.

Nick Garbutt / RF - Red fox (Vulpes vulpes) foraging in snow covered valley. Hayden Valley, Yellowstone National Park, USA. February 2019. (This image may be licensed either as rights managed or royalty free.)

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony, males huddling whilst incubating eggs. Atka Bay, Antarctica. July. Winner of the Portfolio category of the Wildlife Photographer of the Year Awards 2019.

Jordi Chias / Chinstrap penguin (Pygoscelis antarcticus) carcass after leopard seal attack, Antarctic Peninsula, Antarctica.

Jordi Chias / Humped rockcod (Gobionotothen gibberiformis), Antarctic Peninsula, Antarctica.

Jordi Chias / Black rockcod (Notothenia coriiceps), Antarctic Peninsula, Antarctica.

Jordi Chias / Jellyfish (Diplulmaris antarctica) Cuverville, Antarctic Peninsula, Antarctica.

Jordi Chias / Jellyfish (Diplulmaris antarctica). Cuverville, Antarctic Peninsula, Antarctica.

Jordi Chias / Humpback whale (Megaptera novaeangliae), Antarctic Peninsula, Antarctica.

Jordi Chias / Crocodile icefish or White-blooded fish (Channichthyidae), Antarctic Peninsula, Antarctica.

Jordi Chias / Crabeater seals (Lobodon carcinophaga) resting on ice floating ice sheet, Antarctic Peninsula, Antarctica.

Jordi Chias / Rock cod (Notothenia) Antarctic Peninsula, Antarctica.

Jordi Chias / Primnoella soft coral, Antarctic Peninsula, Antarctica.

Jordi Chias / Sponge (Mycale acerata) with diver. Lermaire strait, Antarctic Peninsula, Antarctica.

Jordi Chias / Black rockcod (Notothenia coriiceps), Antarctic Peninsula, Antarctica.

Jordi Chias / Antarctic fur seal (Arctocephalus gazella), Antarctic Peninsula, Antarctica.

Jordi Chias / Antarctic fur seal (Arctocephalus gazella), Antarctic Peninsula, Antarctica.

Jordi Chias / Crabeater seals (Lobodon carcinophaga), Antarctic Peninsula, Antarctica.

Jordi Chias / Humpback whale (Megaptera novaeangliae) spyhopping, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) with mouth open, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx), Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) swimming underwater, Antarctic Peninsula, Antarctica.

Jordi Chias / Crabeater seal (Lobodon carcinophaga) hunting under water, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) swimming, Antarctic Peninsula, Antarctica.

Jordi Chias / Antarctic fur seal (Arctocephalus gazella), Antarctic Peninsula, Antarctica.

Jordi Chias / Weddell seal (Leptonychotes weddellii), Antarctic Peninsula, Antarctica.

Jordi Chias / Weddell seal (Leptonychotes weddellii), Antarctic Peninsula, Antarctica.

Jack Dykinga / Inspiration point covered in snow, Bryce Canyon National Park, USA, January.

Oriol Alamany / Snow leopard (Panthera uncia) female with juvenile, walking in snow, in Spiti Valley, Cold Desert Biosphere Reserve, Himalaya, Himachal Pradesh, India, March

Oriol Alamany / Snow leopard (Panthera uncia) male in snow, in Spiti Valley, Cold Desert Biosphere Reserve, Himalaya, Himachal Pradesh, India, March

Oriol Alamany / Snow leopard (Panthera uncia) female (hiding below the rock) with her two juveniles resting in snow, in Spiti Valley, Cold Desert Biosphere Reserve, Himalaya, Himachal Pradesh, India, March

Jack Dykinga / Landscape of hoodoos in snow at sunrise, Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Winter snow storms cause wind-blown drifting along the canyon rim, Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Conifer tree branch covered in snow and frost from winter snow storm. Bryce Canyon National Park, Utah, USA, January.

Jack Dykinga / Bryce Canyon National Park, Utah. Bristlecone pine clinging to the canyon rim at dawn, Bryce Canyon National Park, Utah, USA, January.

Espen Bergersen / Long-finned pilot whale (Globicephala melas). Kvaloya, Norway.

Espen Bergersen / Humpback whales (Megaptera novaeangliae) showing tail fluke when they dive. Kvanangen, Troms, Norway. December

Espen Bergersen / Humpback whale (Megaptera novaeangliae) feeding around herring fishing vessel. Kvanangen, Troms, Norway. November

Espen Bergersen / Humpback whale (Megaptera novaeangliae) diving. In background a diving boat and 3 divers visible in the water. Kvanangen, Troms, Norway. November

Espen Bergersen / Aerial view of Fin whale (Balaenoptera physalus). Kvanangen, Troms, Norway. November

Espen Bergersen / Sperm whale {Physeter macrocephalus} showint tail fluke as it dives. Photographed just before midnight. 22 nautical miles northwest of Andenes, Northern Norway. July

Espen Bergersen / Killer whale / orca (Orcinus orca). Spyhopping very close, showing eye. Kvanangen, Troms, Norway. November

Espen Bergersen / Humpback whale (Megaptera novaeangliae) showing tail fluke as it dives. Kvanangen, Troms, Norway. November

Espen Bergersen / Killer whales / orcas (Orcinus orca) and boat in background. Kvanangen, Troms, Norway. November

Espen Bergersen / Humpback whales (Megaptera novaeangliae). Kvanangen, Troms, Norway. November

Espen Bergersen / Herring (Clupea harengus) caught in fishing net. Gulls in the net are taking of and flying around, shot with long shutter speed. Norway. December. November

Espen Bergersen / Killer whales / orcas (Orcinus orca). Spyhopping. Kvaloya, Troms, Norway November

Espen Bergersen / Killer whales / orcas (Orcinus orca). Spyhopping. Kvaloya, Troms, Norway October

Espen Bergersen / Killer whales / orcas (Orcinus orca). Spyhopping. Kvaloya, Troms, Norway October

Espen Bergersen / Killer whale / orca (Orcinus orca) splashing with tail fluke. Kvaloya, Troms, Norway October Sequence 4 of 7

Espen Bergersen / Gulls and Killer whales / orcas (Orcinus orca) feeding on herring. Kvaloya, Troms, Norway October

Espen Bergersen / Killer whales / orcas (Orcinus orca) two spyhopping. Kvaloya, Troms, Norway October

Espen Bergersen / Killer whales / orcas (Orcinus orca) two spyhopping. Kvaloya, Troms, Norway October

Espen Bergersen / Killer whale / orca (Orcinus orca) male. Kvaloya, Troms, Norway October

Espen Bergersen / Long-finned Pilot Whale (Globicephala melas) spyhopping, Andfjorden, Andoya, Norway. July

Espen Bergersen / Killer whales / orcas (Orcinus orca) feeding on a bait ball of Herring. Extremely cold conditions (- 15 C) with backlit ice fog. Kvanangen, Troms, Norway. January

Espen Bergersen / Humpback whale (Megaptera novaeangliae) showing tail fluke as it dives. Kvanangen, Troms, Norway. December

Nick Hawkins / Atlantic salmon (Salmon salar) under river ice. Quebec, Canada. October.

SCOTLAND: The Big Picture / Mountain hare, (Lepus timidus), four animals on snowy hillside in winter, Scotland, UK, February.

SCOTLAND: The Big Picture / Mountain hare footprints in snow on mountain top in Glen Coe, Lochaber, Scotland, UK.February

SCOTLAND: The Big Picture / Buacaille Etive Mor and River Etive in winter, Rannoch Moor, Glencoe, Scotland, UK.December

Oscar Dewhurst / Red fox (Vulpes vulpes) sitting on a frozen lake at the edge of the reeds. London, UK. December.

Oscar Dewhurst / Red Fox (Vulpes vulpes) running through deep snow. London, UK. January

Oscar Dewhurst / Red Fox (Vulpes vulpes), hunting in the frost, London, UK. November

Terry Whittaker / Arctic fox (Vulpes lagopus). Blue colour morph. Hornstrandir Nature Reserve, Iceland. March

Marie Read / Snowy Owl (Nyctea scandiaca) female perched, Amherst Island, Ontario, Canada, January.

Marie Read / Loggerhead shrike (Lanius ludovicianus) on an ice-covered fence after an ice storm, Anahuac National Wildlife Refuge, Texas, USA. January.

Marie Read / Northern cardinal (Cardinalis cardinalis) male perched amid snow-covered branches, New York, USA, February.

Marie Read / Common redpoll (Carduelis flammea), male perched in alder (Alnus rugosa) during a snowstorm in winter, New York, USA, January.

David Pattyn / Red fox (Vulpes vulpes) in deep snow emerging from den, Valsavarenche valley, Gran Paradiso national Park, Aosta Valley, Alps, Italy, December

Stefan Christmann / Drifts of snow around glacier, Atka Bay, Queen Maud Land, Antarctica. October 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) chicks lying down in the cold, Atka Bay, Queen Maud Land, Antarctica. October.

Markus Varesvuo / Black woodpecker (Dryocopus martius) male perched on tree trunk, trees covered in hoar frost. Kuusamo, Northern Ostrobothnia, Finland. February. Commended in the Birds in the Environment Category of t...

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) males in breeding colony huddling during winter storm. Atka Bay, Antarctica. July.

Stefan Christmann / Cameraman Lindsay McCrae on ice overlooking Southern Ocean, filming for BBC Dynasties Penguin programme. Atka Bay, Antarctica. March 2017.

Stefan Christmann / Orca (Orcinus orca), two spyhopping in gap in sea ice. Atka Bay, Antarctica. January.

Sven Zacek / Bearded seal (Erignathus barbatus) sunbathing on iceberg broken off from glacier. Kongsfjorden fjord, Spitsbergen, Norway. June 2014.

Sven Zacek / Sun dog over trees in frosty landscape. Tartumaa, Southern Estonia. December 2015.

Sven Zacek / White-tailed sea eagle (Haliaeetus albicilla) flying over frost and snow covered forest. Tartumaa, Southern Estonia. January 2011.

Oriol Alamany / Snow Leopard (Panthera uncia) female with two cubs climbing a canyon cliff at dusk at 4400 metres, Spiti valley, Cold Desert Biosphere Reserve, Himalaya mountains, Himachal Pradesh, India, February

Franco Banfi / Diver exploring an iceberg in Greenland Sea. Tasiilaq, East Greenland. April 2018.

Franco Banfi / Sugar kelp (Saccharina latissima) and Sea anemones (Actiniaria) on rock near iceberg. Tasiilaq, East Greenland. April.

Franco Banfi / Sugar kelp (Saccharina latissima) near iceberg, view upwards to gap in sea ice. Tasiilaq, East Greenland. April.