Nick Garbutt / Aggregation / bloom / swarm of Moon Jellyfish (Aurelia aurita) in the clear waters of Loch Na Keal, off the Isle of Mull, north west Scotland, UK, June, Photographed through the surface.

Alex Mustard / 2020VISION / Basking shark (Cetorhinus maximus) feeding on plankton in the surface waters around the island of Coll, Inner Hebrides, Scotland, UK, June. 2020VISION Book Plate. Did you know? The largest Basking sha...

David Fleetham / Hawksbill Turtle (Eretmochelys imbricata) and a shoal of fish near sea surface. Tubbataha Reef, Philippines.

Mark Brownlow / Sperm whale {Physeter macrocephalus} diving, tail fluke, Kaikoura, South Island, New Zealand

Andy Rouse / Bottlenosed dolphin (Tursiops truncatus) jumping, Caribbean (non-ex). Exclusive jigsaw puzzle rights worldwide sold until 31.12.2014.

Pal Hermansen / Bearded seal (Erignathus barbatus) hauled out on ice, reflected in water. Svalbard, Norway. May.

Danny Green / Sea otter (Enhydra lutris) female and pup playing. Alaska, USA, February.

Danny Green / Sea otter (Enhydra lutris) female and pup. Alaska, USA, February.

Brandon Cole / Oceanic whitetip shark (Carcharhinus longimanus) and Pilotfish (Naucrates ductor) swimming under a stormy surface. Egypt, Red Sea.

Mark Carwardine / Aerial shot zooming in on a superpod of Short-beaked common dolphins (Delphinus delphis), Sea of Cortez, Baja California, Mexico.

Shane Gross / Green sea turtle (Chelonia mydas) near the surface in shallow water, Eleuthera, Bahamas.

Shane Gross / Caribbean reef squid (Sepioteuthis sepioidea) portrait reflecting off the surface of the ocean at night, Eleuthera, Bahamas.

Shane Gross / Portrait of an Atlantic spotted dolphin (Stenella frontalis) reflected at surface, off Bimini, Bahamas.

Alex Mustard / Oceanic whitetip shark (Carcharhinus longimanus) is framed by the surface. Elphinstone reef, Marsa Alam, Egypt. Red Sea.

Shane Gross / Two grey triggerfish (Balistes capriscus) fight over a large piece of plastic floating at the surface among sargassum seaweed (Sargassum natans) in the Sargasso Sea, Atlantic Ocean.

Alex Mustard / Hard corals (including Acropora sp., Platygyra sp. and Pocillopora spp.) growing in shallow water and reflected in the surface. Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea

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

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.

Tony Wu / Bowhead whale (Balaena mysticetus) aerial view, Sea of Okhotsk, Russia.

Tony Wu / Bowhead whales (Balaena mysticetus) in shallow water, Sea of Okhotsk, Russia.

Tony Wu / Bowhead whale (Balaena mysticetus) tail slapping,Sea of Okhotsk, Russia.

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

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

Alex Mustard / Green turtle (Chelonia mydas) descending after breathing at the surface. 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

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

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

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

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

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

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.

Jurgen Freund / Slow motion aerial shot of a Pygmy blue whale (Balaenoptera musculus brevicauda) blowing / breathing at the surface before diving, Banda Sea, Indonesia.

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

David Fleetham / Humpback whale (Megaptera novaeangliae), mother and calf swimming just below surface in front of the West Maui Mountains. South of Lahaina, West Maui, Hawaii.

David Fleetham / Blacktip reef shark (Carcharhinus melanopterus) swimming just below surface at sunset, split level view. Off the island of Yap, Micronesia.

David Fleetham / Great white shark (Carcharodon carcharias), two below surface. Guadalupe Island, Mexico.

David Fleetham / Great white shark (Carcharodon carcharias) dorsal fin visible on surface. Guadalupe Island, Mexico.

David Fleetham / Great white shark (Carcharodon carcharias) breaking surface with mouth open. Guadalupe Island, Mexico.

Tony Wu / Humpback whale (Megaptera novaeangliae australis) female, stationary with calf heading to surface for breath of air. Vava'u, Tonga, South Pacific.