Alex Mustard / A diver explores Silfra Canyon, a deep fault filled with fresh water in the rift valley between the Eurasian and American tectonic plates at Thingvellir National Park, Iceland. May 2011. In this phot...

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 / Spotted Wobbegong (Orectolobus maculatus), Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Grey Nurse Shark (Carcharias taurus), Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Surfer, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Tropical reef, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Red tide, Heron Island, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Tropical island, One Tree Island, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Green Sea Turtle (Chelonia mydas), Heron Island, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Green Sea Turtle (Chelonia mydas), Heron Island, Great Barrier Reef, Queensland, Australia

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

Gary Bell/ Oceanwide / Portuguese Man Of War (Physalia physalis) jellyfish, Coffs Harbor, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Yellow-banded Snapper (Lutjanus adetii) school, Heron Island, Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Portuguese Man Of War (Physalia physalis) jellyfish, Coffs Harbor, Solitary Islands Marine Park, New South Wales, Australia

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 / Blacktip Bullseye (Pempheris affinis) school, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Stripey (Microcanthus strigatus) school, Coffs Harbor, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Eastern Pomfred (Schuettea scalaripinnis) school, Solitary Islands Marine Park, New South Wales, Australia

Gary Bell/ Oceanwide / Zebra Lionfish (Dendrochirus zebra), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Fire Goby (Nemateleotris magnifica), Great Barrier Reef, Queensland, Australia

Gary Bell/ Oceanwide / Painted Sweetlips (Diagramma pictum) in Slender Cardinalfish (Rhabdamia gracilis) school, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Painted Sweetlips (Diagramma pictum) in Slender Cardinalfish (Rhabdamia gracilis) school near Double-headed Maori Wrasse (Cheilinus undulatus), Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Double-headed Maori Wrasse (Cheilinus undulatus), Painted Sweetlips (Diagramma pictum), and Slender Cardinalfish (Rhabdamia gracilis) school, Great Barrier Reef, Queensland, Australia

Lucas Bustamante / Marine Iguanas (Amblyrhynchus cristatus) basking. Fernandina Island, Galapagos Islands.

John Shaw / Great frigatebird (Fregata minor) male at nest site, with gular sac inflated to attract females. Genovesa Island, Galapagos, May.

John Shaw / Sally lightfoot crabs (Grapsus grapsus) on the beach at Puerto Egas, Santiago Island, Galapagos, May.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus), Punta Vicente Roca, Isabela Island, Galapagos

Tui De Roy / Marine iguanas (Amblyrhynchus cristatus) fighting, Punta Vicente Roca, Isabela Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) group on rocks, Cape Douglas, Fernandina Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus), Punta Espinosa, Fernadina Island, Galapagos

Andy Rouse / Galapagos sea lion, (Zalophus wollebaeki), pup on shore, Galapagos.

Andy Rouse / Galapagos sea lion, (Zalophus wollebaeki), swimming upside down, Galapagos

Andy Rouse / Sally lightfoot crab, (Grapsus grapsus), feeding on marine iguana parasites and dead skin, Galapagos

Nick Hawkins / European green crab (Carcinus maenas), an invasive species in North America, Kejimkujik Seaside National Park, Nova Scotia, Canada. July.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) starved to death due to El Nino effect, Puerto Ayora / Academy Bay, Santa Cruz Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) on shore, Punta Moreno, Isabela Island, Galapagos

Shane Gross / Queen conch (Lobatus gigas) laying eggs in the Exuma Cays Land and Sea Park, Exuma, Bahamas.

Gary Bell/ Oceanwide / Golden Damselfish (Amblyglyphidodon aureus) juvenile among coral, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Pink Anemonefish (Amphiprion perideraion) in sea anemone, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Intermediate Cardinalfish (Cheilodipterus intermedius) male incubating eggs in mouth, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Intermediate Cardinalfish (Cheilodipterus intermedius) male incubating eggs in mouth, Great Barrier Reef, Australia

Gary Bell/ Oceanwide / Intermediate Cardinalfish (Cheilodipterus intermedius) male incubating eggs in mouth, Great Barrier Reef, Australia

Nick Hawkins / Rocks and coastal rainforest. Cocos Island National Park, Costa Rica. 2018.

Nick Hawkins / Galapagos sea lion (Zalophus wollebaeki), three resting underneath school bus. Isabela Island, Galapagos. 2017.

Nick Hawkins / Marine iguana (Amblyrhynchus cristatus) basking on volcanic rock at coast. Isabela Island, Galapagos.

Nick Hawkins / Fish seeking shelter around floating tree in open ocean. Off coast of Cocos Island National Park, Costa Rica.

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.

Nick Hawkins / Silky shark (Carcharhinus falciformis). Cocos Island National Park, Costa Rica.

Tui De Roy / Galapagos lava lizard (Microlophus albemarlensis) sitting on Marine iguana (Amblyrhynchus cristatus) Punta Espinosa, Fernandina Island, Galapgos.

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) in water, Puerto Egas, Santiago Island, Galapagos

Tui De Roy / Marine iguanas (Amblyrhynchus cristatus) silhouettes at sunset, Punta Vicente Roca, Isabela Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) males in breeding colouration on rocks, with sun halo, Floreana Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) group on rock in the waves, Cape Hammond, Fernandina Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) swimming underwater, Sullivan Bay, Santiago Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) in the surf, Black Beach, Floreana Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) peering over rocks, Punta Espinosa, Fernandina Island, Galapagos

Tui De Roy / Blue-footed booby (Sula nebouxii), group of eight diving into sea to fish. Punta Gavilanes, Fernandina Island, Galapagos.

Tui De Roy / Blue-footed booby (Sula nebouxii), group fishing underwater. Itabaca Channel, Santa Cruz Island, Galapagos.

Tui De Roy / Blue-footed booby (Sula nebouxii) diving towards sea, folding wings. Northeast coast, Santiago Island, Galapagos. Sequence 1/2.

Tui De Roy / Blue-footed booby (Sula nebouxii) landing. Punta Vicente Roca, Isabela Island, Galapagos.

Tui De Roy / Blue-footed booby (Sula nebouxii) coming in to land. Punta Vicente Roca, Isabela Island, Galapagos.

Tui De Roy / Blue-footed booby (Sula nebouxii) perched on rock at coast. Santa Fe Island, Galapagos. August 2015.

Tui De Roy / Blue-footed booby (Sula nebouxii), pair in courtship display. Punta Pitt, San Cristobal Island, Galapagos. April 2017.

Tui De Roy / Blue-footed booby (Sula nebouxii), five diving into sea. Espumilla Beach, Santiago Island, Galapagos.

Tui De Roy / Red-footed booby (Sula sula), pair nest building in tree. Darwin Bay, Genovesa Island, Galapagos.

Alex Mustard / Remoras (Remora sp.) hitchhiking on the tail of a large (13-15m) female whale shark (Rhincodon typus) swims in open water. Wolf Island, Galapagos National Park, Galapagos Islands. East Pacific Ocean.

Alex Mustard / Galapagos green turtle (Chelonia mydas agassizii) swims over a coral reef. Darwin Island, Galapagos National Park, Galapagos Islands. East Pacific Ocean.

Piotr Naskrecki / African Lungfish (Protopterus annectens), Gorongosa National Park, Mozambique

Magnus Lundgren / Wild Wonders of China / Stellar rockskipper (Entomacrodus stellifer) hiding in a barnacle. Sai Kung East Country Park, Hong Kong, China.

David Fleetham / Goby (Eviota sp) and juvenile porcelain crab (Pteroeides sp), on a Seapen. Komodo National Park, Indonesia.

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) killing tuna. A group of the sea lion bulls have learnt to herd Pelagic yellowfin tuna into a small cove, trapping them. The fish often leap ashore in an effor...

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) hunting tuna. A group of the sea lion bulls have learnt to herd Pelagic yellowfin tuna into a small cove, trapping them. The fish often leap ashore in an effor...

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) hunting tuna. A group of the sea lion bulls have learnt to herd Pelagic yellowfin tuna into a small cove, trapping them. The fish often leap ashore in an effor...

Konrad Wothe / Pheasant (Phasianus colchicus) male calling, East Frisian Islands, Wittbulten National Park. Wadden Sea UNESCO World Heritage Site, Germany, June.

Claudio Contreras / Black grouper (Mycteroperca bonaci) and Caribbean Reef Shark (Carcharhinus perezi), Jardines de la Reina / Gardens of the Queen National Park, Caribbean Sea, Ciego de Avila, Cuba, January

Claudio Contreras / American crocodile (Crocodylus acutus), underwater, Jardines de la Reina / Gardens of the Queen National Park, Caribbean Sea, Ciego de Avila, Cuba, January. Vulnerable species.

Claudio Contreras / Silky shark (Carcharhinus falciformis) two swimming together, Jardines de la Reina / Gardens of the Queen National Park, Caribbean Sea, Ciego de Avila, Cuba, January. Vulnerable species.

Lucas Bustamante / Four Galapagos sea lions (Zalophus wollebaeki) sleeping on beach, Floreana Island, Galapagos, Endangered species.

Alex Mustard / American crocodile (Crocodylus acutus) reflected in the surface as it floats, Jardines de la Reina, Gardens of the Queen National Park, Cuba. Caribbean Sea.

Michel Roggo / Fishes in the Sungai Melinau river, Gunung Mulu National Park, Sarawak, Borneo, Malaysia. Photographed for The Freshwater Project.

Michel Roggo / Freshwater spring in the intertidal zone of the Piccaninnie Ponds Conservation Park, South Australia, Australia. March 2015 . Photographed for The Freshwater Project

Michel Roggo / Rangimairewhenua or Blue Lake, Nelson Lakes National Park, South Island, New Zealand, February 2013. Photographed for The Freshwater Project

Claudio Contreras / Aerial view of Espiritu Santo Island National Park, Sea of Cortez (Gulf of California), Mexico, June, Honorary Mention in the third national contest 'Visions of our Nature' organised by Mexico...

Claudio Contreras / Prickly pear (Opuntia sp.) growing on coastline, Socorro Island, Revillagigedo Archipelago National Park (Socorro Islands), Pacific Ocean, Western Mexico, November, Honorary Mention in the third natio...

Tui De Roy / Split level view of Brown pelicans (Pelecanus occidentalis) feeding, Tortuga Bay, Santa Cruz Island, Galapagos

Tui De Roy / Waved albatross (Phoebastria irrorata) group of three on nest, Punta Suarez, Espanola Island, Galapagos

Tui De Roy / Swallow-tailed gull (Creagrus furcatus) Plazas Island, Galapagos

Tui De Roy / Marine iguana (Amblyrhynchus cristatus) two on beach, Santa Cruz Island, Galapagos.

Ingo Arndt / Double-crested cormorant (Phalacrocorax auritus) adult resting, close up portrait, Everglades National Park, Florida, USA. January. Finalist in the Birds Category of the GDT Awards 2015.

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) waiting for salmon under moonlit sky, Lake Clark National Park, Alaska, USA, August

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) waiting for salmon at full moon, Lake Clark National Park, Alaska, USA, August

Ingo Arndt / Grizzly Bear (Ursus arctos horribilis) two cubs resting, Lake Clark National Park, Alaska, USA, August