Diane McAllister / Polar bears (Ursus maritimus) fighting in water. Beaufort Sea , Kaktovik, Alaska, USA. Highly commended in the Polar Passion category of the Nature's Best Photography Competition 2019.

Alex Mustard / Yellowtail tang (Zebrasoma xanthurum) male and female turn belly to belly during spawning to ensure fertilization. Temple, Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea. This action is very fast...

Claudio Contreras / Californian sea lion (Zalophus californianus) swimming in Southern sea palm (Eisenia arborea) and Giant Kelp (Macrocystis pyrifera) forest, San Benitos Islands, Baja California Pacific Islands Biosphe...

Sergio Hanquet / Arrow crab (Sternorhynchus lanceolatus). Tenerife, Canary Islands.

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 / Brunnich's guillemot (Uria lomvia) colony in mist, many birds in flight and nesting on cliffs. Svalbard, Norway, July 2018.

Danny Green / Ringed seal (Pusa hispida) resting on ice, reflected in water. Svalbard, Norway. July.

Nick Garbutt / Black-browed albatross (Thalassarche melanophris) flying over South Atlantic. Cooper Bay, South Georgia. November.

Alex Mustard / Dugong (Dugong dugon) male and juvenile Golden trevally (Gnathanodon speciosus) swimming over Seagrass (Halophila stipulacea) meadow. Marsa Nabaa, Marsa Alam, Egypt.

Alex Mustard / Green turtle (Chelonia mydas) feeding on Seagrass (Halophila stipulacea), blowing sand out of nostrils, on sea floor. Marsa El Shouna, Marsa Alam, Egypt.

Alex Mustard / Green turtle (Chelonia mydas) resting on sea floor and two juvenile Golden trevally (Gnathanodon speciosus). Marsa El Shouna, Marsa Alam, Egypt.

Alex Mustard / Spinner dolphin (Stenella longirostris) pod socialising close to surface. Fury Shoal, Sataya Reef, Marsa Alam, Egypt.

Alex Mustard / Oceanic whitetip shark (Carcharhinus longimanus) swimming close to surface. Brothers Islands, Egypt.

Shane Gross / Flying fish (Exocoetidae) in Sargasso Sea, Atlantic Ocean.

Guy Edwardes / Milky Way above Durdle Door rock arch. Jurasic Coast, Dorset, England, UK. August 2019. Composite image.

Tony Wu / Humpback whale (Megaptera novaeangliae australis) female with suckling calf. Vava'u Islands, Tonga.

Tony Wu / Humpback whale (Megaptera novaeangliae australis) male calf playing at ocean surface after coming up to breathe. Vava'u Islands, Tonga.

Gary Bell/ Oceanwide / Starfish (Uniophora granifera) on seagrass, Yorke Peninsula, South Australia, Australia

Doug Gimesy / Little blue penguin (Eudyptula minor), two standing on rocks at night, silhouetted against Melbourne city lights. St Kilda breakwater, Victoria, Australia. December 2016. COP26 Countdown Photo Competi...

Tony Heald / Glaucous Gull (Larus hyperboreus) taking off from ice, Svalbard Norway, July.

Pascal Kobeh / False clown anemonefish (Amphiprion ocellaris) in a magnificent sea anemone (Heteractis magnifica), Sulu sea, Philippines

Jordi Chias / Wandering albatross (Diomedea exulans) flying on the open ocean, Drake passage, 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) resting over an iceberg, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) resting over an iceberg, Antarctic Peninsula, Antarctica.

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

Jordi Chias / Leopard seal (Hydrurga leptonyx) resting over an iceberg, Antarctic Peninsula, Antarctica.

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

Jordi Chias / Gentoo penguins (Pygoscelis papua) swimming together and porpoising in search of krill, Antarctic Peninsula, Antarctica.

Jordi Chias / Leopard seal (Hydrurga leptonyx) predating a Gentoo penguin (Pygoscelis papua) Antarctic Peninsula, Antarctica.

Jordi Chias / Gentoo penguins (Pygoscelis papua) walking in line, returning to nesting area, Port Charcot, Antarctic Peninsula, Antarctica.

Jordi Chias / Gentoo penguins (Pygoscelis papua) walking in line, returning to nesting area, Port Charcot, Antarctic Peninsula, Antarctica.

Alex Mustard / California sea lion (Zalophus californianus) pups in an underwater cave. Los Islotes, La Paz, Baja California Sur, Mexico. Sea of Cortez, Gulf of California, East Pacific Ocean.

Alex Mustard / Whale shark (Rhincodon typus) close to the camera with a golden trevally fish (Gnathanodon speciosus) and outline of another whale shark behind , in the plankton-rich green waters of La Paz bay, Baja...

Alex Mustard / RF - Silhouette of a California sea lion (Zalophus californianus) swimming through an underwater cave. Los Islotes, La Paz, Baja California Sur, Mexico. Sea of Cortez, Gulf of California, East Pacific...

Alex Mustard / RF - Basking shark (Ceterhinus maximus) feeding on plankton in Senen Cove, Cornwall, UK. June. (This image may be licensed either as rights managed or royalty free.)

Alex Mustard / Forster's hawkfish (Paracirrhites forsteri) on a coral reef. Jackson Reef, Tiran, Sinai, Egypt. Strait of Tiran, Gulf of Aqaba, Egypt.

Franco Banfi / School of Munk's devil ray, pygmy devil ray, (Mobula munkiana), feeding on plankton at night, photographed on a long exposure, Espiritu Santo Island, Sea of Cortez, Baja California, Mexico, East Pacif...

John Shaw / Great frigatebird (Fregata minor) male at nest site, with gular sac inflated to attract females. Genovesa Island, Galapagos, May.

John Shaw / Black-browed albatross pair (Thalassarche melanophris) mutual grooming during copulation. New Island, Falkland Islands, November.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) cleaned by a Bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Shane Gross / Pelagic thresher shark (Alopias pelagicus) being cleaned by a bluestreak cleaner wrasse (Labroides dimidiatus) at Monad Shoal off Malapascua Island, Philippines.

Andy Rouse / Galapagos sea lion, (Zalophus wollebaeki), pup on shore, Galapagos.

Andy Rouse / Galapagos sea lion, (Zalophus wollebaeki), swimming upside down, Galapagos

Georgette Douwma / Nudibranch (Chromodoris willani) with a scale worm. Lembeh Strait, North Sulawesi, Indonesia.

Doc White / Sea Otter, (Enhydra lutris), young male, Elkhorn Slough, California, USA. January

John Chan / California sea lion (Zalophus californianus) feeding on a Striped bass (Morone saxatilis), Southern California, USA.

SCOTLAND: The Big Picture / Blue mussels (Mytilus edulis) with encrusting marine life, Sula Sgeir, Scotland. UK, July

SCOTLAND: The Big Picture / Aerial view of nesting Gannets (Morus bassanus) and swirling seas, Hermaness, Shetland, Scotland, UK, October.

SCOTLAND: The Big Picture / Puffin (Fratercula arctica) silhouetted at sunset on Hermaness, Shetland, Scotland, UK, June.

SCOTLAND: The Big Picture / Puffins (Fratercula arctica) Shaint Isles, Scotland, UK, June.

SCOTLAND: The Big Picture / Northern gannets (Morus bassanus) diving for fish, split level shot, Shetland, Scotland, UK, July.

SCOTLAND: The Big Picture / Northern gannets (Morus bassanus) diving for fish, split level shot, Shetland, Scotland, UK, September.

SCOTLAND: The Big Picture / Kelp forest (Laminaria digitata) with small fish, Shetland, Scotland, UK, July.

Ross Hoddinott / Sand dunes, marram grass (Ammophila arenaria) and beach at sunrise, Luskentyre, Isle of Harris, Scotland, UK. October 2018

Marie Read / Horned Puffin (Fratercula corniculata) flying over a pattern of kelp and sea foam, photographed from above, St. Paul, Pribilof Islands, Alaska, USA. July.

Marie Read / Abstract patterns of reflected sky and clouds on the ocean with a silhouetted Red-faced cormorant (Phalarocorax urile) in flight, St. Paul Island, Pribilof Islands, Alaska, USA, July.

Marie Read / Great blue heron (Ardea herodias) in breeding plumage, head and shoulders showing plumes on crown and neck, Montezuma National Wildlife Refuge, New York, USA, May.

Mark Carwardine / Aerial view Fin whales (Balaenoptera physalus) lunge-feeding in the southern Sea of Cortez (Gulf of California), Baja California, Mexico.

Mark Carwardine / Aerial view of Fin whale (Balaenoptera physalus) lunge-feeding, with throat pouch distended, southern Sea of Cortez (Gulf of California), Baja California, Mexico.

Mark Carwardine / Aerial view Fin whales (Balaenoptera physalus) lunge-feeding in the southern Sea of Cortez (Gulf of California), Baja California, Mexico.

Mark Carwardine / Aerial view Fin whales (Balaenoptera physalus) lunge-feeding in the southern Sea of Cortez (Gulf of California), Baja California, Mexico.

Pascal Kobeh / Trumpetfish (Aulostomus chinensis) on the coral drop off, Sulu Sea, Philippines.

Franco Banfi / California sealion (Zalophus californianus) swimming. Magdalena Bay, Baja California Sur, Pacific Ocean, Mexico

Franco Banfi / Striped marlin (Tetrapturus audax) feeding on Sardine (Sardinops sagax). Magdalena Bay, Baja California Sur, Pacific Ocean, Mexico.

David Fleetham / Humpback whale (Megaptera novaeangliae) breaching, watched by paddle boarder. Canoe Beach, Maui. Hawaii. October 2010. Model released. Digital composite.

SCOTLAND: The Big Picture / Puffins (Fratercula arctica) and Razorbills (Alca torda) with Eilean Mhuire behind, Shiant Isles, Outer Hebrides, Scotland, UK. June, 2018

Juan Carlos Munoz / Griffon vulture (Gyps fulvus) landing on coast next to flock. Cantabria, Spain, March.

Alex Hyde / Southern Elephant Seal bull (Mirounga leonina) close up portrait, King Haakon Bay, South Georgia. November.

Alex Hyde / Southern Elephant Seals (Mirounga leonina) pup with mother. King Haakon Bay, South Georgia. November.

Alex Hyde / King penguins (Aptenodytes patagonicus). Grytviken, South Georgia. November.

Alex Hyde / Colonies of King penguins (Aptenodytes patagonicus) and Southern Elephant Seals (Mirounga leonina) on beach at St. Andrews Bay, South Georgia. November.

Alex Hyde / King penguins (Aptenodytes patagonicus) group of three on the shore, St. Andrews Bay, South Georgia. November.

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

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

Guy Edwardes / Great peacock anemone (Anemone pavonia), Meteora, Greece.

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

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

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

Danny Green / Sea otter (Enhydra lutris) resting on sea ice, Alaska, USA, June

Danny Green / Sea otter (Enhydra lutris) resting amongst sea ice, Alaska, USA, June

Danny Green / Sea otters (Enhydra lutris) resting on ice, Alaska, USA, June

Nick Hawkins / Rocks and coastal rainforest. Cocos Island National Park, Costa Rica. 2018.

Nick Hawkins / Galapagos sea lion (Zalophus wollebaeki), three resting underneath school bus. Isabela Island, Galapagos. 2017.

Nick Hawkins / Marine iguana (Amblyrhynchus cristatus) basking on volcanic rock at coast. Isabela Island, Galapagos.

Nick Hawkins / Fish seeking shelter around floating tree in open ocean. Off coast of Cocos Island National Park, Costa Rica.

Nick Hawkins / Galapagos green turtle (Chelonia mydas agassizi) swimming above sea floor with shoal of fish in background. Off San Cristobal Island, Galapagos.

Nick Hawkins / Silky shark (Carcharhinus falciformis). Cocos Island National Park, Costa Rica.

Pal Hermansen / Avalanche on Gullemot (Uria aalge) nesting cliff on first day birds return to breed. Finnmark, Norway. March.

Chris Gomersall / Bottlenose dolphin (Tursiops truncatus) breaching. Moray Firth, Scotland.

Andy Sands / Oxlips (Primula eliator) growing among Wood Anemones (Anemone nemorosa) good indicators of ancient woodland, Suffolk, England, UK, April

David Fleetham / Clark's anemonefish (Amphiprion clarkii), pair tending to egg mass placed beside the protection of an anemone. Yap, Micronesia.

David Fleetham / Bargibant's pygmy seahorse (Hippocampus bargibanti) wrapped around Eye fan coral (Cnidaria sp). Philippines.