Alex Mustard / Southern stingray (Dasyatis americana) two swimming over sand bar, under stormy sky. Grand Cayman, Cayman Islands. British West Indies.

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.

Nick Hawkins / American lobster (Homarus americana) in eelgrass (Zostera marina). Nova Scotia, Canada. July

Shane Gross / Queen conch (Lobatus gigas) juvenile feeding on algae growing on Seagrass (Thalassia testudinum) blades. Eleuthera, Bahamas.

Jurgen Freund / Moral eels, Urchins, Cuttlefish, Shrimp and other marine life living within a discarded tyre and fishing net under a ships' harbour, Maluku, Indonesia. November.

Georgette Douwma / Ribbon eel ( Rhinomuraena quaesita) Lembeh Strait, North Sulawesi, Indonesia.

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 / Sergeant major (Abudefduf sp) schooling in mangroves of Isabela Island, Galapagos.

Jurgen Freund / Timelapse of Giant sea cucumbers (Thelenota ananas) moving underwater, with a Giant clam (Tridacna gigas) in the background, Great Barrier Reef, Queensland, Australia, 2015.

David Fleetham / Day / Big blue octopus (Octopus cyanea) with diver in background. Hawaii. September 2012.

David Fleetham / Whitetip reef shark (Triaenodon obesus) resting on sea floor. Kauai, Hawaii.

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

Alex Mustard / Tawny nurse shark (Nebrius ferrugineus) group, individuals circling each other at dusk. Vavuu Atoll, Maldives. Indian Ocean.

Alex Mustard / Hawksbill turtle (Eretmochelys imbricata) pair circling each other above coral reef. Seven Mile Beach, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea.

Alex Mustard / RF - Southern stingray (Dasyatis americana) swimming over sand in shallow water at dawn, Cayman Islands, Caribbean Sea. (This image may be licensed either as rights managed or royalty free.)

Claudio Contreras / American crocodile (Crocodylus acutus) resting just above seagrass underwater, Banco Chinchorro Biosphere Reserve, Caribbean region, Mexico

Tony Wu / Juvenile Australian sea lion (Neophoca cinerea) resting in shallows, possibly to thermoregulate, Carnac Island, Western Australia.

Alex Mustard / Hedgehog seahorse (Hippocampus spinosissimus) female moves over a sandy seabed. Dauin, Negros Island, Philippines. Bohol Sea, tropical west Pacific Ocean.

Georgette Douwma / Chocolate chip sea star o (Protoreaster nodosus) on sandy bottom. Mabul, Malaysia.

Alex Mustard / Diver (Predrag Vuckovic) is dwarfed by Great hammerhead shark (Sphyrna mokarran). This species can reach over 6m in length. South Bimini, Bahamas. The Bahamas National Shark Sanctuary. Gulf Stream, We...

Claudio Contreras / Green turtle (Chelonia mydas) Akumal, Caribbean Sea, Mexico, January. Endangered species.

Claudio Contreras / Green turtle (Chelonia mydas) over sea floor, Akumal, Caribbean Sea, Mexico, January. Endangered species.

Claudio Contreras / Green turtle (Chelonia mydas) wide angle view of fin, Akumal, Caribbean Sea, Mexico, January. Endangered species.

Franco Banfi / Green moray (Gymnothorax funebris) Santa Lucia, Camaguey, Cuba, Caribbean Sea, Atlantic Ocean

Franco Banfi / Corals attached to structure of bio-rock, a method of enhancing the growth of corals and aquatic organisms, Karang Lestari Pemuteran project, Desa Pemuteran, Bali Island, Indonesia, Pacific Ocean.

Franco Banfi / Tiger shark (Galeocerdo cuvier) Northern Bahamas, Caribbean Sea, Atlantic Ocean.

Franco Banfi / Scuba diver and Tiger shark (Galeocerdo cuvier) Northern Bahamas, Caribbean Sea, Atlantic Ocean. March 2009.

Alex Mustard / Reef octopus (Octopus cyanea) portrait near wreck. Gubal Island, Egypt. Red Sea.

Alex Mustard / Group of predators hunting together, in an example of 'Nuclear foraging'. The Moray eel (Gymnothorax javanicus) flushes out prey, and is followed by a Napolean wrasse (Cheilinus undulatus) and a Bluef...

Alex Mustard / Tasseled wobbegong shark (Eucrossorhinus dasypogon) yawning. Citrus Ridge, Yanggefo Island, Gam Island, Raja Ampat, West Papua, Indonesia.

Alex Mustard / Galapagos sea lions (Zalophus wollebaeki) young playing in shallow water. Floreana Island, Galapagos Islands, Ecuador. East Pacific Ocean

Alex Mustard / Hairy pipehorse (Acentronura dendritica) female swimming over the seabed with her prehensile tail in the air. Bloody Bay Wall, Little Cayman, Cayman Islands. Caribbean Sea.

Doug Perrine / Barjacks (Caranx ruber), Yellowtail snapper (Ocyurus chrysurus), and Sergeant major damselfish (Abudefduf saxatilis) swimming around wreck of bow gun on C-58 shipwreck off Puerto Morelos, near Cancun,...

Georgette Douwma / Coral line nursery with Acropora corals grown to reintroduce to the Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Erect rope sponge (Amphimedon compressa) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stove-pipe sponge (Aplysina archeri) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Erect rope sponge (Amphimedon compressa) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Georgette Douwma / Stove-pipe sponge (Aplysina archeri) and Orange elephant ear sponge (Agelas clathrodes) Bonaire, Netherlands Antilles, Caribbean, Atlantic Ocean.

Jurgen Freund / Giant clam (Tridacna gigas) Raja Ampat, West Papua, Indonesia.

Doug Perrine / Mediterranean monk seal (Monachus monachus) adult male swimming, Deserta Grande, Ilhas Desertas, Parque Natural da Madeira, Portugal, Atlantic Ocean, June. Critically endangered species

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

Richard Robinson / Featherstar (Crinoidea) on red coral (Errina novazelandiae) in Doubtful Sound, Fiordland National Park, New Zealand.

Pascal Kobeh / Aggregation of thousands of Spider crabs (Leptomithrax gaimardii) for moulting, South Australia Basin, Australia. Pacific Ocean.

Pascal Kobeh / Aggregation of thousands of Spider crabs (Leptomithrax gaimardii) for moulting, South Australia Basin, Australia. Pacific Ocean.

Pascal Kobeh / Marine iguana (Amblyrhynchus cristatus) swimming back to the surface, Galapagos. Pacific ocean.

Sue Daly / Close up of the face of a Brill (Scophthalmus rhombus), swims out of frame, Sark, British Channel Islands, UK, August.

Sue Daly / Brill (Scophthalmus rhombus) camouflaged on the seabed, Sark, British Channel Islands, UK, August.