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...

Alex Mustard / Yellow tube sponge (Aplysina fistularis) on coral reef, diver exploring in background. Black Rock Drop Off, East End, Grand Cayman, Cayman Islands, British West Indies. Model released.

Alex Mustard / Two female Common seahorses (Hippocampus kuda) fighting over territory on the seabed. The brief fight was preceeded by a ritualised, synchronised parade. Bitung, North Sulawesi, Indonesia. Lembeh Stra...

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

Milan Radisics / Aerial shot of yellow mineral sediments flowing into the Atlantic Ocean, near Stokkseyri, Southern Iceland, August 2018.

Shane Gross / Elkhorn corals (Acropora palmata) at night silhouetted by a scientist's light during the annual coral spawn. Abaco, Bahamas.

Nick Hawkins / Sugar kelp (Sacchinaria latissima) off Nova Scotia, Canada. September

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

Franco Banfi / Freshwater turtle (Trachemys scripta venusta) swimming amongst Water lilies leaves, Gran Cenote, near Tulum, Quintana Roo, Yucatan Peninsula, Mexico.

Nick Upton / European eel (Anguilla anguilla) elver migrating upstream, using an eel pass on the side of a weir, Somerset Levels, England, UK, July.

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.

Franco Banfi / Close view of a Green anaconda, (Eunectes murinus) underwater, Formoso River, Bonito, Mato Grosso do Sul, Brazil

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

Dave Bevan / Male Blackbird (Turdus merula) catching European eel (Anguilla anguilla) elvers as they migrate up a waterfall, Ceredigion, Wales, UK, July.

Dave Bevan / Male Blackbird (Turdus merula) catching European eel (Anguilla anguilla) elvers as they migrate up a waterfall, Ceredigion, Wales, UK, July.

Dave Bevan / European eel (Anguilla anguilla) elvers migrating up a wet rock next to a waterfall, Ceredigion, Wales, UK, July.

Alex Mustard / Yellowtail tang (Zebrasoma xanthurum) male courting a female prior to spawning at dusk on a coral reef. Temple, Ras Umm Sid, Sharm El Sheikh, Sinai, Egypt. Red Sea.

Guy Edwardes / Trees reflected in Loch Tummel, Perthshire, Scotland, UK. October, 2014.

David Fleetham / Cleaner wrasse (Labroides dimidiatus) swimming alongside Golden damsel (Amblyglyphidodon aureus) looking for parasites, Fiji, Pacific Ocean.

Claudio Contreras / Californian Sealion (Zalophus californianus) in kelp (Macrocystis pyrifera) forest, San Benito del Este Island, Baja California Peninsula Pacific Islands Biosphere Reserve, Baja California, Mexico, Ma...

Theo Bosboom / Yellow coloured Birch leaf (Betula) floating on the bubbles and foam of a stream, De Veluwe (Leuvenumse bos), Netherlands.

Terry Whittaker / Water vole (Arvicola amphibius) feeding on Yellow flag iris (Iris pseudacorus) seed pods, Kent, England, UK. October.

Nick Upton / Eurasian beaver (Castor fiber) feeding on grass amongst Meadow buttercups (Ranunculus acris) near a pond in a large enclosure, Devon, England, UK, June. Captive.

Sue Daly / Feather duster fan worm (Sabella spallanzanii) with tentacles moving in the current, Sark, British Channel Islands, UK, August.

Sue Daly / Furbelows seaweed (Saccorhiza polyschides), with fronds moving in the current, Sark, British Channel Islands, UK, June.

Alex Mustard / Yellow tube sponge (Aplysina fistularis) on a coral reef, with the camera rotated during the long exposure. East End, Grand Cayman, Cayman Islands. British West Indies. Caribbean Sea.

Alex Mustard / Ribbon sweetlips (Plectorhinchus polytaenia) USAT Liberty Wreck, Tulamben, Bali, Indonesia. Java Sea

SCOTLAND: The Big Picture / Grey seal (Halichoerus grypus) swimming over kelp forest, Shetland, Scotland, UK, August.

Willem Kolvoort / Water filled ditch with shadow of a tree on water with Fringed waterlily (Nymphoides peltata) Star duckweed (Lemna trisulca) Netherlands. July 2015. Commended in the Underwater World Category of the G...

Neil Aldridge / Yellow-billed stork (Mycteria ibis) catching a young barbel or catfish in the shallows of the Chobe River, Chobe National Park, Botswana.

Alex Mustard / Spotlight goby (Gobiosoma louisae) looking out from inside a Yellow tube sponge (Aplysina fistularis), growing on a coral reef. Bloody Bay Wall, Little Cayman, Cayman Islands, British West Indies. Car...

Alex Mustard / California sea lion (Zalophus californianus) resting in the canopy of a forest of giant kelp (Macrocystis pyrifera). Santa Barbara Island, Channel Islands. Los Angeles, California, United States of Am...

Alex Mustard / Young California sea lion (Zalophus californianus) playing in the canopy of a forest of Giant kelp (Macrocystis pyrifera). Santa Barbara Island, Channel Islands. California, USA. North East Pacific Oc...

Alex Mustard / Red Irish lord (Hemilepidotus hemilepidotus) resting on a yellow sponge, in front of red soft coral (Eunephthya rubiformis). Browning Pass, Port Hardy, Vancouver Island, British Columbia. Canada. Nor...

Solvin Zankl / Thongweed (Himanthalia elongata) edible plant sold as 'Sea Spaghetti' for human consumption. From Roscoff, France, April. Preserved specimen.

Solvin Zankl / Kelp forest (Laminaria hyperborea), Atlantic Ocean, North West Norway, March.

Pascal Kobeh / Long-snouted seahorse (Hippocampus guttulatus) with prehensile tail twined round seagrass, Etang de Thau Lagoons, Languedoc-Roussillon, France.

Jeff Vanuga / Ephydrid flies (Ephydra sp) that eat microscopic algae and survives during the winter in thermal pools. Biscut Basin, Yellowstone National Park, Wyoming, USA, January.

Brent Stephenson / Sunset off Scott Island, with floating pieces of sea ice, Scott Inlet, Baffin Island, Canadian Arctic, August 2015.

Claudio Contreras / Mesoamerican slider turtle / terrapin (Trachemys scripta venusta) in sinkhole, Cenote Carwash, near Tulum, Yucatan Peninsula, Mexico, January

Claudio Contreras / Mesoamerican slider turtle / terrapin (Trachemys scripta venusta) in sinkhole, Cenote Carwash, near Tulum, Yucatan Peninsula, Mexico, January

Georgette Douwma / Blue triggerfish (Pseudobalistes fuscus). Egypt, Red Sea. Indo-Pacific.

Bence Mate / Great white egret (Ardea alba) silhouetted at sunset, Lake Csaj, Pusztaszer, Hungary, February. Winner of the Portfolio category of the Terre Sauvage Nature Images Awards competition 2015.

Bence Mate / Great egret (Ardea alba) hunting fish, Lake Csaj, Pusztaszer, Hungary, February. Winner of the Portfolio category of the Terre Sauvage Nature Images Awards competition 2015.

Alex Mustard / Portrait of a Severn's pygmy seahorse (Hippocampus severnsi) at Mioskon Island, Raja Ampat, West Papua, Indonesia. Dampier Strait. Tropical West Pacific Ocean.

Alex Mustard / Black hamlet (Hypoplectrus nigricans) and Yellowbelly hamlet (Hypoplectrus aberrans) spawning at dusk. As this genus is quite recently evolved hybridization is still possible. Hamlets are one of the...

Alex Mustard / Yellow tube sponges (Aplysina fistularis) growing on a Caribbean coral reef. Cayman Brac, Cayman Islands. Caribbean Sea.

Alex Mustard / Saddleback anemonefish (Amphiprion polymnus) in anemone home, Anilao, Batangas, Luzon, Philippines. Verde Island Passages, Tropical West Pacific Ocean.

Alex Mustard / Harlequin sweetlips (Plectorhinchus chaetodonoides) cleaned by a pair of bluestreak cleaner wrasse (Labroides dimidiatus). South Atoll, Tubbataha Atolls, Tubbataha Reefs Natural Park, Palawan, Philipp...

Juan Carlos Munoz / People exploring underground lakes via rigid inflatable boat, Cross Cave (Krizna jama) under Cross Mountain, Green Karst, Slovenia, October 2014.

Solvin Zankl / Tiny crab on Broad-toothed Gulfweed (Sargassum fluitans) Sargassum Community. Sargasso Sea, Bermuda

George Sanker / North American beaver (Castor canadensis). swimming in late evening light, Acadia National Park, Maine, USA., September.

Andy Rouse / Galapagos sea lion (Zalophus wollebaeki) silhouetted at sunset, Galapagos.

Juan Manuel Borrero / Pearl cichlid (Geophagus brasiliensis) captive, occurs in Brazil and Uruguay.

Yukihiro Fukuda / Light trails of Japanese fireflies (Hotaria parvula and Luciola cruciata), Nichinan-chou, Tottori, Japan, July, Endemic species.

Jurgen Freund / Blue and yellow fusiliers (Caesio teres) shoal, Great Barrier Reef, Queensland, Australia.

Ole Jorgen Liodden / Campbell albatross (Thalassarche impavida) in flight, silhouetted at sunset, near Campbell Islands, Sub-Antarctic New Zealand. February.

Juergen Freund / Banded sea kraits (Laticauda colubrina) around the roots of mangrove tree, split level. Mali Island, Macuata Province, Fiji, South Pacific.

Juergen Freund / Detail of Giant kelp (Macrocystis pyrifera) gas-filled bladders (pneumatocysts) Vancouver Island, British Columbia, Vancouver Island, Canada.

Chris & Monique Fallows / King penguin (Aptenodytes patagonicus) colony at sunrise. Grytviken, South Georgia Island.

Markus Varesvuo / Puffin (Fratercula arctica) silhouetted at sunset, Shetland Islands, Scotland, UK, July.

Andy Rouse / Gentoo penguin (Pygoscelis papua) jumping onto beach, Carcass Island, Falkland Islands.

Ole Jorgen Liodden / Svalbard reindeer (Rangifer tarandus platyrhyncus) feeding at sunset, Spitsbergen, Svalbard, Norway, April.

Andy Trowbridge / Two Yellow-eyed penguin (Megadyptes antipodes) chicks standing together. Otago Peninsula, Otago, South Island, New Zealand, January. Endangered Species.

Constantinos Petrinos / Yellow stripe clingfish (Diademichthys lineatus) living in association with the Fire Urchin (Astropyga radiata) Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Chromodorid nudibranch (Chromodoris annae) on Sea Squirt (Polycarpa aurata) Lembeh Strait, North Sulawesi, Indonesia.

Constantinos Petrinos / Sunset reflected on the surface of the Aegean Sea on a calm day with a speedboat, Evia Island, Greece. July 2014.

Espen Bergersen / Humpback whales (Megaptera novaeangliae) and Killer whale (Orcinus orca) feeding on a bait ball of Herring. Andfjorden close to Andoya, Nordland, Northern Norway. January.

Espen Bergersen / Humpback whale (Megaptera novaeangliae) with fin above water, Andfjorden close to Andoya, Nordland, Northern Norway. January.

David Pattyn / Black necked grebe (Podiceps nigricollis) pair at night, performing their courtship dance during the mating season, with street lights reflected in the water. The Netherlands.April 2014

Espen Bergersen / Adult male King eider (Somateria spectabilis) close up portrait, Batsfjord, Norway, March.

Espen Bergersen / Male King eiders (Somateria spectabilis) three taking-off from water. Batsfjord, Norway, March.

Pal Hermansen / Aerial view of river delta and coast, South West Iceland, June 2014.

Pal Hermansen / Aerial view of river delta, South West Iceland, June 2014.

Nick Garbutt / Yellow Anaconda (Eunectes notaeus) in vegetation at the edge of the Paraguay River, Taiama Reserve, western Pantanal, Brazil, South America.

Markus Varesvuo / Great White Egret (Egretta alba) with water splashing from beak, Hungary January

David Noton / Cyclists riding bikes along riverside path at dawn, near Vang Vieng, Laos, March 2009.

Bernard Castelein / Reflection in fen on surface of water, Klein Schietveld, Brasschaat, Belgium, November.

Pascal Kobeh / Group of California sea lions (Zalophus californianus) in a kelp forest (Macrocystis pyrifera), California, USA. Pacific ocean.

Pascal Kobeh / Group of California sea lions (Zalophus californianus) swimming in kelp forest (Macrocystis pyrifera), California, USA. Pacific ocean.

Markus Varesvuo / Head portrait of juvenile Northern Goshawk (Accipiter gentilis) drinking, Hungary, May. Magic Moments book plate.

Andy Rouse / Bengal Tiger (Panthera tigris tigris) male 'Romeo T6' cooling off in waterhole during hot summer. Ranthambore National Park, India.

Alex Mustard / Split level view of shallow coral reef in the Red Sea at sunset. Gordon Reef, Sinai, Egypt. Strait of Tiran, Gulf of Aqaba, Red Sea.

Olga Kamenskaya / Ice pile of broken shelf ice, near the shore of Lake Baikal, Siberia, Russia, March.

Jean E. Roche / Flooded cars in scrapyard in Arles city flooded by the Rhone in December 2003. Camargue, France.

Loic Poidevin / Female Grizzly bear (Ursus arctos horribilis) in water, Khutzeymateen Grizzly Bear Sanctuary, British Columbia, Canada, June.

Ben Hall / Great crested grebe (Podiceps cristatus) pair performing courtship displaying at dawn, backlit and surrounded by mist, Cheshire, UK, April. Highly honoured in the Birds Category of Nature's Best Windl...

Alex Mustard,Alex Mustard / A portrait of a nudibranch ( Limacia clavigera) searching for food on algae. Gulen, Norway. North East Atlantic Ocean.

Alex Mustard / Butterfish (Pholis gunnellus) portrait. Gardur, south west Iceland. North Atlantic Ocean.

Ernie Janes,Ernie Janes / Yellow Labrador jumping breakwater, Norfolk. April

Laurent Geslin / Male tufted duck (Aythya fuligula) on water. Walthamstow reservoir, London, UK