Ismaele Tortella / White tailed eagle (Haliaeetus albicilla) catching fish, Lofoten, Norway, August.

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...

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

Tony Wu / Bowhead whale (Balaena mysticetus), group socialising in shallow water, aerial view. Part of larger group of more than 50 whales congregating, Sea of Okhotsk sub-population, Russia.

Tony Wu / Humphead parrotfish (Bolbometopon muricatum) shoal spawning in early morning, part of mass aggregation of thousands of fish. Caroline Islands, Palau.

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

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.

Shane Gross / Caribbean reef shark (Carcharhinus perezi), two from below, one close up. Caribbean Sea off Gardens of the Queen National Park, Cuba.

Shane Gross / American crocodile (Crocodylus acutus) with open mouth amongst Seagrass (Alismatales). Gardens of the Queen National Park, Cuba.

Gary Bell/ Oceanwide / Sea Goldie (Pseudanthias squamipinnis) school in coral reef with feather stars, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Veined Octopus (Octopus marginatus) predating urchin, Anilao, Philippines

Gary Bell/ Oceanwide / Piling with sponges, tunicates, and ascidians, Yorke Peninsula, South Australia, Australia

Gary Bell/ Oceanwide / Sea Anemone (Corynactis australis) group, Bicheno, Tasmania, Australia

Gary Bell/ Oceanwide / Candy Cane Sea Star (Fromia monilis), Anilao, Philippines

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Scarlet Cleaner Shrimp (Lysmata amboinensis) cleaning mouth of Tomato Grouper (Cephalopholis sonnerati), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Black-spot Goatfish (Parupeneus signatus) and Goldlined Seabream (Rhabdosargus sarba) school, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Oriental Flying Gurnard (Dactyloptena orientalis) with pectoral fins extended in defense posture, Anilao, Philippines

Theo Bosboom / Rocks and sea stacks in the surf at Playa del Silencio in Asturias on the Northwest coast of Spain. May 2015

Theo Bosboom / Sea stacks consisting of flysch rock battered by the incoming tide, playa de Gueirua, Asturias, Northwest Spain. October 2015

Theo Bosboom / Wave breaking in front of the two famous sea stacks Risin and Kellingin on the Faroe Islands. March 2018.

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

Doug Perrine / Dugong or Sea cow (Dugong dugon) split level view, Calauit Island, off Busuanga, Calamian Islands, Palawan, Philippines.

Alex Mustard / Split level image of Leather corals (Sarcophyton sp.) flourishing in shallow water close to uninhabited coral islands. Misool, Raja Ampat, West Papua, Indonesia. Ceram Sea. Tropical West Pacific Ocean...

Alex Mustard / Commensal emperor shrimp (Periclimenes imperator) moves across the colourful red patterned surface of its host Candycane sea cucumber (Thelenota rubralineata). Misool, Raja Ampat, West Papua, Indonesi...

Alex Mustard / Killer whales (Orcinus orca) at the surface in an Arctic fjord in Spildra, northern Norway, with sea birds. Arctic Ocean

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 / Tawny nurse sharks (Nebris ferrungineus) at night. Vavuu Atoll, Maldives. Indian Ocean

Alex Mustard / Midnight snapper (Macolor macularis) shelters in a cavern on a coral reef with white soft corals (Scleronephthya sp.) and solderfish. Vavuu Atoll, Maldives. Indian Ocean

Alex Mustard / Pair of Western clown anemonefish (Amphiprion ocellaris) spawning orange eggs on the rock beneath their Magnificent sea anemone (Heteractis magnifica) home on a coral reef. This photo shows the larger...

Alex Mustard / Common seahorse (Hippocampus kuda) female wrapping her prehensile tail around piece of wood on the seabed. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Shoal of three Bigfin reef squid (Sepioteuthis lessoniana) in open water at night. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Portrait of a Giant frogfish (Antennarius commersoni) on a large Yellow elephant ear sponge (Ianthella basta). Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

Alex Mustard / Portrait of a tarpon (Megalops atlanticus) on a coral reef. East End, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Alex Mustard / Portrait of a male short snouted seahorse (Hippocampus hippocampus) in sea oak seaweed (Halidrys siliquosa). Devon, England, United Kingdom. British Isles. English Channel. North East Atlantic Ocean.

Alex Mustard / Blue whale (Balaenoptera musculus) swims beneath the surface of the ocean. Indian Ocean, off Sri Lanka.

Alex Mustard / Pod of False killer whales (Pseudorca crassidens) swimming beneath the surface of the ocean. Indian Ocean, off Sri Lanka.

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

Alex Mustard / Blacktip reef shark (Carcharhinus melanopterus) swims through schools of fish. Misool, Raja Ampat, West Papua, Indonesia. Ceram Sea. Tropical West Pacific Ocean.

Alex Mustard / Carapace of a dead olive Ridley turtle (Lepidochelys olivacea) entangled in discarded fishing gear. Indian Ocean, off Sri Lanka.

Franco Banfi / Pod of sperm whale socializing, (Physeter macrocephalus), Dominica, Caribbean Sea, Atlantic Ocean.

Jack Dykinga / Bald eagle (Haliaeetus leucocephalus) perched as Snow geese (Chen caerulescens) fly by, Bosque del Apache National Wildlife Refuge, New Mexico, USA, January.

Ernie Janes / Bald eagle (Haliaeetus leucocephalus) portrait, captive, occurs in North America.

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...

Shane Gross / Pygmy seahorse (Hippocampus bargibanti) holding on to a branch of a sea fan coral. Malapascua, Philippines.

Shane Gross / Graysby fish (Cephalopholis cruentata) a type of grouper, hiding in a sponge off Eleuthera, Bahamas.

Ernie Janes / Sea asters (Aster tripolium) in discarded car tyres, Norfolk, England, UK. September.

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

Nick Hawkins / Steller's sea lions (Eumetopias jubatus) off the coast of the Great Bear Rainforest, near Bella Bella, British Columbia, Canada. August

Nick Hawkins / A group of frilled anemones (Metridium senile) off Bonaventure Island in the Gulf of Saint Lawrence, Quebec, Canada. September.

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

SCOTLAND: The Big Picture / Dead man's fingers (Alcyonium digitatum) on a rocky reef with view of the sky, Shetland, Scotland, UK, August.

SCOTLAND: The Big Picture / Close up of a Long clawed squat lobster (Munida rugosa) in Loch Carron, January 2016.

SCOTLAND: The Big Picture / Close up of a colony of Jewel anemones (Corynactis viridis) Scotland, UK, October.

SCOTLAND: The Big Picture / Maiden's salp (Thetys vagina) , west coast of 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 of Fin whale (Balaenoptera physalus) lunge-feeding, with mouth open and 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.

Shane Gross / A small aggreggation of queen conch (Lobatus gigas) off Cat Island, Bahamas

Ralph Pace / Green Sea Turtle (Chelonia mydas), San Diego, California

Ralph Pace / Olive Ridley Sea Turtle (Lepidochelys olivacea) females coming ashore to nest during arribada, Playa de Escobilla Sanctuary, Oaxaca, Mexico

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

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

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

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) breeding colony, males huddling on sea ice during polar night, incubating eggs, ice shelf in background. Atka Bay, Antarctica. July 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony huddled during polar night, males incubating eggs. Atka Bay, Antarctica. July 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) colony huddling, males incubating eggs, on sea ice under full moon in polar night. Atka Bay, Antarctica. July 2017.

Stefan Christmann / Member of BBC Dynasties crew photographing on sea ice in light of full moon, during polar night. Atka Bay, Antarctica. July 2017.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) breeding colony on sea ice, ice shelf in background. Atka Bay, Antarctica. August.

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) breeding colony, mainly males brooding eggs, huddled together on sea ice. Atka Bay, Antarctica. June.

Stefan Christmann / Cameraman Lindsay McCrae filming Emperor penguin (Aptenodytes forsteri) colony for BBC Dynasties Penguin programme. Chicks are on sea ice whilst parents fish at sea. Atka Bay, Antarctica. December 201...

Stefan Christmann / Emperor penguin (Aptenodytes forsteri) group sliding over sea ice, returning to form breeding colony. Iceberg in background. Atka Bay, Antarctica. April 2017.

Ismaele Tortella / White tailed eagle (Haliaeetus albicilla) flying, Lofoten, Norway, August.

Espen Bergersen / Photographer and Hvitserkur. Hvitserkur, a 15 m-high sea stack just off shore on the eastern side of Vatnsne, Iceland. October.

Espen Bergersen / Hvitserkur, 15 m-high sea stack just off shore on the eastern side of Vatnsne, Iceland, May.

Peter Lewis / Starling (Sturnus vulgaris) murmuration at sunset, West Pier, Brighton, England, UK.

Pascal Kobeh / Pair of courting Egg-eating / Turtleheaded sea snakes (Emydocephalus annulatus) New Caledonia, Pacific Ocean.

Pascal Kobeh / Pair of courting Egg-eating / Turtleheaded sea snakes (Emydocephalus annulatus) New Caledonia, Pacific Ocean.

Pascal Kobeh / Pair of courting Egg-eating / Turtleheaded sea snakes (Emydocephalus annulatus) New Caledonia, Pacific Ocean.

Pascal Kobeh / Pair of courting Egg-eating sea snakes / Turtleheaded sea snakes (Emydocephalus annulatus) New Caledonia, Pacific Ocean.

Pascal Kobeh / Close-up of a Egg-eating / Turtleheaded sea snake (Emydocephalus annulatus) with eggs coming out of its mouth, New Caledonia, Pacific Ocean.

Pascal Kobeh / Reef covered with two red Stomphia sea anemones (Stomphia coccinea), with Plumose anemones (Metridium senile), Red soft corals (Eunephthya / Gersemia rubiformis) and Green sea urchins (Strongylocentro...

Pascal Kobeh / Diver on a reef covered with Plumose anemones (Metridium senile) Gulf of Saint Lawrence, Canada