Alex Mustard / A large colony of Mountainous star coral (Montastraea faveolata) spawning at night on a coral reef, showing the synchronous release of bundles of eggs and sperm, East End, Grand Cayman, Cayman Islands...

Georgette Douwma / Yellowbar angelfish (Pomacanthus maculosus) swimming over coral reef with soft corals. Egypt, Red Sea.

Claudio Contreras / French Angelfish (Pomacanthus paru) with a Smallmouth Grunt (Haemulon chrysargyreum) and Blade Fire Coral (Millepora complanata). Cancun National Park, Caribbean Sea, Mexico.

Claudio Contreras / Queen Angelfish (Holacanthus ciliaris) among other coral fish. Cancun National Park, Caribbean Sea, Mexico.

Alex Mustard / Grey angelfish (Pomacanthus arcuatus) portrait, Georgetown, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea.

Alex Mustard / Rock beauty angelfish (Holacanthus tricolor) pair at dusk performing their courtship dance with the larger male circling the female, Georgetown, Grand Cayman, Cayman Islands, British West Indies. Cari...

Inaki Relanzon / Whitsunday Islands, aerial view, Great Barrier Coral Reef, Queensland, Australia, October 2011.

Pete Oxford / Caribbean reef shark (Carcharhinus perezi) Jardines de la Reina National Park, Cuba

Roberto Rinaldi / John Dory fish (Zeus faber) on coral reef, Strait of Messina, Southern Italy

Juergen Freund / Green turtles (Chelonia mydas) mating over coral reef, Sipadan Island, Sabah, Malaysia, June, Endangered species

Juergen Freund / Split level image of Papuan fisherman standing on his dugout canoe over shallow corals, New Ireland, Papua New Guinea, June 2010

Juergen Freund / Lunar tailed rock cod / Coronation grouper (Variola louti) swimming fast over coral reef, Bali, Indonesia

Juergen Freund / Coral reef with hard corals and cabbage coral, Komodo NP, Indonesia

Juergen Freund / Split level of snorkeler over coral reef on white sandy seabed contrasting with dry topside landscape in background, Komodo NP, Indonesia, August 2009. Model released.

Juergen Freund / Fluorescent corals. Misool, Raja Ampat, West Papua, Indonesia

Juergen Freund / Split-level shot of coral reef and island. Misool, Raja Ampat, West Papua, Indonesia, January 2010

Juergen Freund / Fluorescent corals, Misool, Raja Ampat, West Papua, Indonesia

Juergen Freund / Baby green turtle (Chelonia mydas) hatchling in the shallows of the beach, swimming out to sea. Anano Island, Wakatobi, South Sulawesi, Indonesia, November

Juergen Freund / Umbrella and other human waste thrown out into the coastal waters, settling on the ground becoming marine life habitat, Moluccas Islands, Indonesia, December 2009

Juergen Freund / Hermit crab with shell covered in soft coral (Heteroxenia fuscescens) Lembeh Strait, North Sulawesi, Indonesia

Juergen Freund / Green sea turtle (Chelonia mydas) resting in a crevice in the coral reef. Sipadan Island, Semporna, Sabah, Malaysia, June

Juergen Freund / Colorful coral reef with soft corals (Alcyonacea) and fan corals (Gorgonacea). Misool, Raja Ampat, West Papua, Indonesia, January

Juergen Freund / Fluorescent coral viewed under normal light, Misool, Raja Ampat, West Papua, Indonesia, sequence 1/2

Juergen Freund / Fluorescent coral viewed under UV light, Misool, Raja Ampat, West Papua, Indonesia, sequence 2/2

Juergen Freund / Old coral reef destroyed by dynamite fishing. New corals are not able to colonise the rubble. Misool, Raja Ampat, West Papua, Indonesia, January 2010

Georgette Douwma / Giant Frogfish (Antennarius commerson) on coral reef. The animal can vary greatly in colour and pattern. Bali, Indonesia, December.

Pete Oxford / Bladed Fire Coral (Millepora Complanata) causes sting on contact, Belize Barrier Reef, Belize

Jeff Rotman / Klunzinger's wrasse (Thalassoma rueppellii / klunzingeri) swimming past diver, Sinai Peninsula, Red Sea, Egypt. Model released. Model released.

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

Alex Mustard / Caribbean reef shark (Carcharhinus perezi) swimming over a coral reef, beneath a snorkeler and boat. Near Grand Bahama, Bahamas. Tropical West Atlantic Ocean.

Alex Mustard / A Caribbean reef shark (Carcharhinus perezi) above corals and sponges on a reef. Grand Bahama, Bahamas.

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

Alex Mustard / Caribbean Reef Shark (Carcharhinus perezi) portrait in blue water above a coral reef. Grand Bahama, Bahamas. March

Luciano Candisani / Sebastiao Gomes Reef, Caravelas, southern Bahia, Brazil

Georgette Douwma / Golden damselfish (Amblyglyphidodon aureus) swimming past coral reef wall with colourful soft corals. Bali, Indonesia.

Jeff Rotman / Free diver swimming in shallow water over coral reef, Sinai, Egypt, Red Sea Model released Model released.

Jeff Rotman / Free diver exploring blue water beside coral reef, Sinai, Egypt, Red Sea Model released Model released.

Jeff Rotman / Free diver coming up from dive to explore coral reef, Sinai, Egypt, Red Sea Model released Model released.

Georgette Douwma / Coral reef scenery with Gorgonian and shoal of Pygmy / Glassy sweepers (Parapriacanthus guentheri) Egypt, Red Sea

Juergen Freund / Charlotte Watson snorkels down to collect sand which may contain polychaete worms, Coral Reef census, Lizard Island, Queensland, Australia, April 2008. Model released

Georgette Douwma / Lyretail anthias / Goldies (Pseudanthias squamipinnis) on coral reef with soft corals, Red Sea, Egypt

Fred Bavendam / Butterfly Perch (Caesioperca lepidoptera) group swimming around two sponges, Tasmania, Australia

Chris Newbert / Hawksbill Sea Turtle (Eretmochelys imbricata) and Leather Coral (Sarcophyton sp) on reef, Indonesia

Chris Newbert / Soft Coral (Dendronephthya sp) on reef, Indonesia

Georgette Douwma / Emperor angelfish (Pomacanthus imperator). Red Sea, Egypt.

Georgette Douwma / Big-eye or Goggle-eye (Priacanthus hamrur) on wreck. Note colour change from deep red to silver. Egypt, Red Sea

Georgette Douwma / Emperor angelfish (Pomacanthus imperator) with Lyretail anthias / Goldies (Pseudanthias squamipinnis). Red Sea, Egypt (Digital composite)

Ingrid Visser / Coral reefs and islands, Kimbe Bay, West New Britain Island, Papua New Guinea

Norbert Wu / Caribbean Reef Shark (Carcharhinus perezii) swimming through reef and schooling fish, Bahamas, Caribbean

Chris Newbert / Reef scenic, 80 feet deep, Solomon Islands

Flip Nicklin / Squirrelfish (Holocentrus sp) schooling at reef, Cocos Island, Costa Rica

Flip Nicklin / Squirrelfish (Holocentrus sp) schooling at reef, Cocos Island, Costa Rica

Norbert Wu / Green Sea Turtle (Chelonia mydas) being cleaned by Yellow-eyed Surgeonfish (Ctenochaetus strigosus), Hawaii

Konrad Wothe / Bottlenose Dolphin (Tursiops truncatus) pair swimming over coral reef, Honduras

Chris Newbert / Reef scenic at one-hundred-twenty feet, showing Soft Corals, Sea Fans, Crinoids, Leather Corals, Sea Whips and Sponges, Solomon Islands

Birgitte Wilms / Diana's Hogfish (Bodianus diana) and Soft Coral (Dendronephthya sp), Red Sea, Egypt

Chris Newbert / Underwater reef scene with Sea Whips, Gorgonian Whip Coral, blossoming Soft Corals, Guard Plate Coral, and schools of Pseudanthias, Red Sea, Egypt

Chris Newbert / Double-headed Maori Wrasse (Cheilinus undulatus) swimming over coral reef, Red Sea, Egypt

Chris Newbert / Right-handed Hermit Crab (Paguritta sp) colony in Hump Coral (Porites sp), Solomon Islands

Chris Newbert / Soft Coral (Dendronephthya sp) schooling Pygmy Sweeper (Parapriacanthus ransonneti) and Lionfish (Pterois volitans)

Chris Newbert / Fan Coral (Melithaea sp) group and Feather Star (Oxycomanthus bennetti), Solomon Islands

Chris Newbert / Soft Coral (Dendronephthya sp) outcroppings and Basslet (Pseudanthias sp), Red Sea, Egypt

Chris Newbert / Green Sea Turtle (Chelonia mydas) swimming, Galapagos Islands, Ecuador

Chris Newbert / Batfish (Platax sp) schooling, Red Sea, Egypt

Chris Newbert / Stony Coral (Acropora sp) and baitfish, Solomon Islands

Chris Newbert / Sponge (Latrunculia magnifica) surrounded by Basslet (Pseudanthias sp) and Soft Coral (Dendronephthya sp), Jackson Reef, Red Sea

Chris Newbert / Mushroom Coral (Fungia fungites) detail, Palau

Norbert Wu / Sergeant Major (Abudefduf vaigiensis) with Basslet (Pseudanthias sp) and Fairy Basslet (Pseudanthias squamipinnis) schools around coral reef, Australia

Norbert Wu / Sipadan Island, a rich oceanic island surrounded by coral reef, Borneo

Chris Newbert / Reef scenic, many species of Soft Coral and Basslet (Pseudanthias sp) school, 50 feet deep Solomon Islands

Chris Newbert / Pygmy Sweeper (Parapriacanthus ransonneti) school in cave, Red Sea, Egypt

Chris Newbert / Green Sea Turtle (Chelonia mydas) swimming over coral reef, 40 feet deep, Red Sea, Egypt

Chris Newbert / Soft Coral (Dendronephthya sp) outcroppings, Sea Fan (Subergorgia sp) and Glassfish (Parapriacanthus ransonneti)

Chris Newbert / Elephant Ear Sponge (Ianthella basta) and schooling Barracuda (Sphyraena genie) in background, 110 feet deep, Solomon Islands

Chris Newbert / Feather Star (Colobometra perspinosa) on Sea Fan (Melithaea sp) and Leather Coral (Sarcophyton sp) 70 Feet Deep, Solomon Islands

Norbert Wu / Hawksbill Sea Turtle (Eretmochelys imbricata) underwater, Sipadan Island, Borneo

Fred Bavendam / Green Sea Turtle (Chelonia mydas), Galapagos Islands, Ecuador

Fred Bavendam / Collared Butterflyfish (Chaetodon collare) school, Andaman Sea, Thailand

Fred Bavendam / Garden of Hard Corals just beneath the water's surface at Bunaken Island, Manado Tua Marine National Park, Manado, North Sulawesi, Indonesia

Fred Bavendam / Variety of small reef fish swimming in the currents above a Hard Coral reef with Sponges, Ascidians, and a blue Sea Star, Manado, North Sulawesi, Indonesia

Fred Bavendam / Diagonal-banded Sweetlips (Plectorhinchus lineatus) school, Loloata Resort, Papua New Guinea

Fred Bavendam / Longfin Bannerfish (Heniochus acuminatus) pair, Bali, Indonesia

Fred Bavendam / Scalloped Hammerhead Shark (Sphyrna lewini) swimming among reef fish Galapagos Islands, Ecuador

Flip Nicklin / Coral and schooling fish, Gray's Reef National Marine Sanctuary, Georgia

Fred Bavendam / Eyepatch Butterflyfish (Chaetodon adiergastos) school swimming along shallow reef, Bali, Indonesia

Fred Bavendam / Basslet (Pseudanthias sp) school, swimming near a Sea Fan (Melithaea sp) and a Blue Sea Star (Linckia laevigata)

Fred Bavendam / Several species of Basslets (Pseudanthias sp) swarming above a Columnar Leaf Coral (Pavona clavus), Milne Bay, Papua New Guinea

Flip Nicklin / Corals in shallow water, Great Barrier Reef, Australia

Tui De Roy / Palm trees and water flowing on beach on Palmyra Atoll, a wet, equatorial atoll with fringing reefs, native forests and abundant seabirds, Palmyra Atoll National Wildlife Refuge, US Line Islands

Fred Bavendam / Staghorn Coral (Acropora cervicornis) colony with an extensive bleached area at its center, Kimbe Bay, Papua New Guinea

Juergen Freund / Feather star {Crinoidea} on fan coral, Indo Pacific

Juergen Freund / Ornate ghost pipefish on coral reef {Solenostomus paradoxus} Indo-Pacific

Juergen Freund / Featherstar in fan coral {Crinoidea} Indo-Pacific

Georgette Douwma / Hard coral polyps {Mycedium elephantotus} Borneo, Indonesia

Georgette Douwma / Hard coral polyps {Euphyllia ancora} Bunaken, Sulawesi, Indonesia

Georgette Douwma / Golden damselfish juveniles {Amblyglyphidodon aureus} with coral. Andaman sea, Thailand