Steven Kazlowski / Moose (Alces alces) bull adult swims across a lake in Denali National Park, Interior of Alaska, summer, USA

Nick Upton / Coot (Fulica atra) swims on lake with colourful autumnal tree leaves reflected in the water around its own reflection, Wiltshire, UK, October

Juergen Freund / Snorkeler swims amongst Sergeant major damselfish (Abudefduf vaigiensis) at the house reef of Miniloc Island Resort, El Nido Island, Palawan, Philippines, May 2009. These fish gather in a dense mass w...

Alex Mustard / A Leafy Seadragon (Phycodurus eques) swims over a seagrass bed. Wool Bay Jetty, Edithburgh, Yorke Peninsular, South Australia, November.

Nick Upton / 2020VISION / Northern shoveler drake (Anas clypeata) reflected in calm water as it swims among reeds and rushes in flooded marshland on a sunny winter afternoon. Greylake RSPB reserve, Somerset Levels, UK, January

Alex Mustard / A young California sealion (Zalophus californianus) swims in a shallow pool. Los Isotes, La Paz, Mexico. Sea of Cortez, East Pacific Ocean.

Alex Mustard / Caribbean reef shark (Carcharhinus perezi) swims over a coral reef. Grand Bahama Island, Bahamas. Tropical West Atlantic Ocean.

Alex Mustard / Draughtsboard Shark / Australian Swellshark (Cephaloscyllium laticeps) swims through a giant kelp forest (Macrocystis pyrifera). Like a pufferfish, this species of shark is able to rapidly swell with...

Philip Dalton / Nile Crocodile (Crocodylus niloticus) approaching Common Zebra (Equus burchellii) as it swims across Mara river during migration, Masai Mara GR, Kenya

Philip Dalton / Nile Crocodile (Crocodylus niloticus) grabbing Common Zebra (Equus burchellii) as it swims across Mara river during migration, Masai Mara GR, Kenya

Philip Dalton / Nile Crocodile (Crocodylus niloticus) grabbing Common Zebra (Equus burchellii) as it swims across Mara river during migration, Masai Mara GR, Kenya

Georgette Douwma / Martha Holmes swims with Whale Shark off Hawaii, 1991 on location for BBC NHU television series "Seatrek", Model released

Doug Perrine / Newborn Lemon shark pup swims away from mother {Negaprion brevirostris} Bahamas, Caribbean (Non-ex).

Doug Allan / Weddell seal swims under ice {Leptonychotes weddelli} Antarctica. Weddell seals can dive to a depth of 700m!

Steven Kazlowski / Sockeye salmon (Oncorhynchus nerka) adult swims upstream to spawn, interior of Alaska, USA

Alex Mustard / A diver swims with an aggregation of Atlantic cod (Gadus morhua) over a kelp forest. These cod were gathered in early spring off the north coast of Iceland to spawn. Thorshofn, Iceland. North Atlantic...

Alex Mustard / A diver swims with an aggregation of atlantic cod (Gadus morhua) over a kelp forest, fish approximately 1m in length, cod were gathered in early spring off the north coast of Iceland to spawn. Thorsho...

Alex Mustard / A diver swims with an aggregation of Atlantic cod (Gadus morhua) over a kelp forest, fish approximately 1m in length. These cod were gathered in early spring off the north coast of Iceland to spawn....

Alex Mustard / Tropical blue ringed octopus (Hapalochlaena lunulata) free swims just above the seabed. Lembeh Strait, Molucca Sea Sulawesi, Indonesia

Alex Mustard / Pfeffer's flamboyant cuttlefish (Metasepia pfefferi) walks across the seabed using special flaps on the underside of its body, and its outermost arms as four legs. This species rarely swims. Lembeh St...

Alex Mustard / An Atlantic long arm octopus (Octopus defilippi) swims across the seabed. This is a typical swimming posture for long arm octopus, but it has been suggested as mimicking a poisonous sole in the mimic...

Alex Mustard / Southern / pacific blue-ringed octopus (Hapalochlaena maculosa) swims across the seabed. Port Philip Bay, Blairgowrie, Melbourne, Victoria, Australia.

Nick Upton / Greylag goose (Anser anser) approaches in an aggressive threat display posture as it swims on a lake, Wiltshire, UK, October

Nick Upton / Coot (Fulica atra) swims on lake with autumnal tree leaves reflected in the water around its own reflection, Wiltshire, UK, October

Nick Upton / Male Coot (Fulica atra) fighting a rival in a territorial dispute, as its partner swims towards them, Wiltshire, UK, October

Nick Upton / Mallard (Anas platyrhynchos) drake swims on lake among fallen oak tree leaves, Wiltshire, UK, November

Nick Upton / Greylag goose (Anser anser) swimming in courtship posture with its neck stretched out low to the water as it swims, Wiltshire lake, UK, October

Steven Kazlowski / Brunnich's guillemot (Uria lomvia) parent swims with its chick along the northwestern coast of Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean, July

Steven Kazlowski / Polar bear (Ursus maritimus) adult swims in waters along Spitsbergen and the northwestern coast of the Svalbard Archipelago, Norway, Greenland Sea, July

Steven Kazlowski / Adult bull Walrus (Odobenus rosmarus) swims underwater, along Spitsbergen and the northwest coast of the Svalbard Archipelago, Norway, Arctic Ocean, July

Steven Kazlowski / Brunnich's guillemot (Uria lomvia) parent swims with its chick along the northwestern coast of Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean, July

Nick Upton / Coot (Fulica atra) preening as it swims on lake. Wiltshire, UK, March.

Alex Mustard / A Leafy Seadragon (Phycodurus eques) swims over seagrass meadow. Wool Bay, Edithburgh, South Australia, November.

Alex Mustard / A colourful Weedy Seadragon (Phyllopteryx taeniolatus) swims in front on kelp. Weedy Seadragons vary greatly in colour across their range, this individual is typical of Tasmania. Waterfall Bay, Eagle...

Alex Mustard / A Leafy Seadragon (Phycodurus eques) swims over seagrass. Wool Bay Jetty, Edithburgh, Yorke Peninsular, South Australia, November.

Alex Mustard / An adult Leafy Seadragon (Phycodurus eques) swims over a bed of seagrass. Wool Bay Jetty, Edithburgh, Yorke Peninsular, South Australia, November.

Alex Mustard / A diver watching a Weedy Seadragon (Phyllopteryx taeniolatus) as it swims over a seagrass meadow. Flinders Jetty, Mornington Peninsular, Victoria, Australia, March.

Alex Mustard / A male Weedy Seadragon (Phyllopteryx taeniolatus) carrying eggs along tail swims through a Kelp (Macrocystis pyrifera) forest in Tasmania, Australia. Tasmania is the only part of Australia with giant...

Nick Upton / Northern shoveler drake (Anas clypeata) reflected in calm water as it swims among reeds and rushes in flooded marshland on a sunny winter afternoon. Greylake RSPB reserve, Somerset Levels, UK, January

Alex Mustard / A young California sealion (Zalophus californianus) swims in a shallow pool. Los Isotes, La Paz, Mexico. Sea of Cortez, East Pacific Ocean.

Alex Mustard / A school of baitfish parting as a large bull California sealion (Zalophus californianus) swims through as he patrols his territory. Los Islotes, La Paz, Baja California, Mexico. Sea Of Cortez, East Pa...

Alex Mustard / A young California sealion (Zalophus californianus) swims in the rocky shallows. Los Isotes, La Paz, Mexico. Sea of Cortez, East Pacific Ocean.

Alex Mustard / Snorkellers photographing a Florida manatee (Trichechus manatus latirostrus) as it swims through Three Sister's Spring. Crystal River, Florida, USA. February 2010

Alex Mustard / A lone Florida manatee (Trichechus manatus latirostrus) swims up into the Three Sisters Spring. Crystal River, Florida, USA. February 2010

Alex Mustard / Caribbean reef shark (Carcharhinus perezi) swims over large sponges on a coral reef. Grand Bahama Island, Bahamas. Tropical West Atlantic Ocean.

Alex Mustard / Caribbean reef shark (Carcharhinus perezi) swims over coral reef, underneath the silhouette of a boat, Grand Bahama Island, Bahamas. Tropical West Atlantic Ocean.

Alex Mustard / Lemon shark (Negaprion brevirostris) swims through Gorgonian corals in shallow water. Little Bahama Bank. Bahamas. Tropical West Atlantic Ocean.

Alex Mustard / A nine-foot (3m) Lemon shark (Negaprion brevirostris) accompanied by Remora and Jacks, swims over the Sugar Wreck. Little Bahama Bank, Bahamas.

Alex Mustard / Bottlenose dolphin (Tursiops truncatus) swims beneath the surface over a shallow ridge. Sandy Ridge, Little Bahama Bank, Bahamas. Tropical West Atlantic Ocean.

Alex Mustard / A lemon shark (Negaprion brevirostris) drags its pectoral fin through the sand as it swims accompanied by Remoras / Sharksuckers (Echeneis naucrates). Little Bahama Bank. Bahamas. Tropical West Atlant...

Alex Mustard / Caribbean reef shark (Carcharhinus perezi) swims under a boat. Grand Bahama Island, Bahamas. Tropical West Atlantic Ocean.

Jeff Rotman / Silvertip Shark (Carcharhinus albimarginatus) swims with schooling Pilot Fish (Naucrates ductor), Cocos Island, Costa Rica, Pacific Ocean.

Doug Perrine / Whale shark {Rhincodon typus} swims amongst spawning Mutton snappers {Lutjanus analis} Gladden Spit and Silk Cayes Marine Reserve, Belize, Central America, Caribbean Sea

Jeff Rotman / Diver Swims through Giant Kelp Forest, California, Pacific Ocean Model released.

Solvin Zankl / Close up of Sea snail {Atlanta peroni}, a marine deepsea pteropod, Atlantic ocean. This animal swims using the long wings near its head as oars. Digital focus stacking.

Birgitte Wilms / Goldspotted Eel (Myrichthys oculatus) lives in the sand bottom and only occasionally swims around, 40 feet deep, Indonesia

Jeff Rotman / Snorkler swims beside wild Bottlenose dolphin (Tursiops truncatus) at night, Red Sea, Egypt Model released.

Jeff Rotman / Bottlenose dolphin {Tursiops truncatus} swims with sick child and child therapist. Dolphin Reef, Red Sea, Eliat, Israel Model released.

Doug Perrine / Hawaiian monk seal (Monachus schauinslandi) Critically endangered, juvenile female swims over coral reef at Mahukona, Kohala, Hawaiian Island, Central Pacific Ocean

Doug Perrine / Hawaiian monk seal (Monachus schauinslandi) Critically endangered, juvenile female with flipper tag swims over coral reef at Mahukona, Kohala, Hawaiian Island, Central Pacific Ocean

Doug Perrine / Hawaiian monk seal (Monachus schauinslandi) Critically endangered, juvenile female with flipper tag swims over coral reef at Mahukona, Kohala, Hawaiian Island.

Doug Perrine / Hawaiian monk seal (Monachus schauinslandi) Critically endangered, juvenile female with flipper tag swims around coral reef at Mahukona, Kohala, Hawaiian Island, Central Pacific Ocean

Doug Perrine / Hawaiian monk seal (Monachus schauinslandi) Critically endangered, juvenile female swims over coral reef at Mahukona, Kohala, Hawaiian Island. Scar on back is from satellite transmitter glued on by re...

Jane Burton / Duckling swims underwater among goldfish (digitally enhanced)

Juergen Freund / Richard Fitzpatrick swims with drowsy Tiger shark {Galeocerdo cuvieri} to rouse it back into movement after attaching satellite transmitter, Great Barrier Reef & Coral Sea, Australia

Doug Perrine / Newborn Lemon shark (Negaprion brevirostris) swims from mother to protection in mangroves, Bahamas

Norbert Wu / Antarctic Minke Whale (Balaenoptera bonaerensis) spyhopping, swims under ice edge in search of plankton, McMurdo Sound, Antarctica

Norbert Wu / Antarctic Minke Whale (Balaenoptera bonaerensis) hunted by the Japanese, swims off ice edge, McMurdo Sound, Antarctica

Tui De Roy / Leopard Seal (Hydrurga leptonyx) swims around Adelie Penguins (Pygoscelis adeliae) standing on ice floe, Hope Bay, Antarctic Peninsula, Antarctica

Michael Quinton / Trumpeter Swan (Cygnus buccinator) female incubating eggs as male swims nearby, North America

Norbert Wu / Antarctic Minke Whale (Balaenoptera bonaerensis) breathing in small pool of open water in ice channel, swims under ice edge for plankton, McMurdo Sound, Antarctica

Norbert Wu / Antarctic Minke Whale (Balaenoptera bonaerensis) breathing in small pool of open water in ice channel, swims under ice edge for plankton, McMurdo Sound, Antarctica

Mark Moffett / Carpenter Ant (Camponotus sp) swims unharmed in digestive juices of pitcher plant collecting large prey which would otherwise decompose and turn juices foul The symbiotic relationship benefits both an...

Mark Moffett / Carpenter Ant (Camponotus sp) swims unharmed in digestive juices of pitcher plant collecting cricket prey which would otherwise decompose and turn juices foul, the symbiotic relationship benefits both...

Juergen Freund / Seahorse fisherman at night swims below lantern on his boat, Handumon, Bohol Is, Philippines

Jeff Rotman / Feather Star {Lamprometra klunzingeri} swims while filter feeding at night, Red Sea.

Andrew Parkinson / Water vole swims under bridge through duckweed {Arvicola terrestris} Derbyshire, UK

Ben Osborne / Olive ridley turtle swimming at surface. Costa Rica {Lepidochelys olivacea}

Jose B. Ruiz / Marbled electric ray swims away from sandy seabed {Torpedo marmorata} Mediterranean

Andrew Parkinson / Water vole swims with ivy leaf for bedding {Arvicola terrestris} Cromford canal, UK

Jeff Rotman / Man swims with lemon Caribbean reef shark (Carcharhinus perezi) Bahamas Model released.

John Downer / Nigel Williams, foster parent to imprinted Greylag chicks, swims in pool for filming of BBC tv series 'Supernatural'

John Downer / Nigel Williams acting as foster parent to imprinted Greylag chicks swims in pool for filming of BBC tv series 'Supernatural'

John Downer / Nigel Williams swims with imprinted Greylag goose chicks for filming of BBC tv series 'Supernatural'

Doug Allan / Weddell seal swims under ice {Leptonychotes weddelli} Antarctica

Juergen Freund / Cowtail ray / Feathertail stingray swims away from sand on seabed {Pastinachus sephen} Great Barrier Reef, Australia

GEORGETTE DOUWMA / Lined sweetlips fish swims with shoal of Large-eyed jacks. Digitally manipulated image

GEORGETTE DOUWMA / One Raccoon butterflyfish swims in opposite direction to shoal of bannerfish. Digitally manipulated image

Angelo Giampiccolo / A school of Red mullets (Mullus surmuletus) swims in the wreck of the SS Thistlegorm.

Mark Moffett / Carpenter Ant (Camponotus sp) swims unharmed in digestive juices of pitcher plant collecting large prey which would otherwise decompose and turn juices foul The symbiotic relationship benefits both an...

Mark Moffett / Carpenter Ant (Camponotus sp) swims unharmed in digestive juices of pitcher plant collecting large prey which would otherwise decompose and turn juices foul The symbiotic relationship benefits both An...

DAVID TIPLING / Chinese muntjac deer swims across lake {Muntiacus reevesi} Europe

Peter Scoones / Humphead (Napoleon) wrasse {Cheilinus undulatus} swims over bleached coral. Maldives

Ben Osborne / Olive ridley turtle swims in sea with head out. Costa Rica {Lepidochelys olivacea}