Mangrove snappers (Lutjanus griseus), schooling in Hol Chan Marine Preserve, inside the Mesoamerican Barrier Reef, Belize

Nurse sharks (Ginglymostoma cirratum), being fed in shark and ray alley, Caye Caulker, Mesoamerican Barrier Reef, Belize

Southern stingray (Hypanus americanus) with snorkeler in shark and ray alley, Caye Caulker, Mesoamerican Barrier Reef, Belize

Southern stingray (Hypanus americanus) being fed in shark and ray alley, Caye Caulker, Mesoamerican Barrier Reef, Belize

Southern stingray (Hypanus americanus) with snorkeler in shark and ray alley, Caye Caulker, Mesoamerican Barrier Reef, Belize

Tarpon (Megalops atlaticus), underwater at feeding station inside the Mesoamerican Barrier Reef, Belize

West Indian manatee (Trichechus manatus), on the reef near Caye Caulker, inside the Mesoamerican Barrier Reef, Belize

West Indian manatee (Trichechus manatus), with snorkeler near Caye Caulker, inside the Mesoamerican Barrier Reef, Belize

West Indian manatee (Trichechus manatus), with snorkelers near Caye Caulker, inside the Mesoamerican Barrier Reef, Belize

Soft corals and sponges underwater on Long Caye in the Mesoamerican Barrier Reef, Belize

Soft corals and sponges underwater on Long Caye in the Mesoamerican Barrier Reef, Belize

A myriad of hard and soft corals, as well as tropical reef fish on the healthy reef near Volivoli Resort on Viti Levu, Fiji, South Pacific, Pacific

Nurse shark (Ginglymostoma cirratum), on the sand in Hol Chan Marine Preserve, inside the Mesoamerican Barrier Reef, Belize

Nurse shark (Ginglymostoma cirratum), on the sand in Hol Chan Marine Preserve, inside the Mesoamerican Barrier Reef, Belize

A myriad of fish and coral underwater at Hol Chan Marine Preserve, inside the Mesoamerican Barrier Reef, Belize

Snorkeler with golden jellyfish (Mastigias papua etpisoni), in Jellyfish Lake, a marine lake located on Eil Malk island, Rock Islands, Palau, Micronesia, Pacific

Nurse sharks (Ginglymostoma cirratum), being fed in Hol Chan Marine Preserve, inside the Mesoamerican Barrier Reef, Belize

Nurse sharks (Ginglymostoma cirratum), being fed in Hol Chan Marine Preserve, inside the Mesoamerican Barrier Reef, Belize

Green sea turtle (Chelonia mydas), surfacing for air near Caye Caulker, inside the Mesoamerican Barrier Reef, Belize

A myriad of fish and coral underwater at Hol Chan Marine Preserve, inside the Mesoamerican Barrier Reef, Belize

Split image of pristine coral reef and island, Rongelap, Marshall Islands, Micronesia, Pacific

Blue-green chromis (Chromis viridis), Rongelap, Marshall Islands, Micronesia, Pacific

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with boat silouhette above, Little Cayman Island, Cayman Islands, Caribbean

Eye detail, green sea turtle (Chelonia mydas), Kailua-Kona, Hawaii, United States of America, Pacific

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef, Little Cayman Island, Cayman Island, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming in open water with scuba diver, Little Cayman Island, Cayman Island, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with underwater photographer, Cayman Brac, Cayman Island, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef, Little Cayman Island, Cayman Island, Caribbean

Green sea turtle (Chelonia mydas), Kailua-Kona, Hawaii, United States of America, Pacific

Mangrove in Truk lagoon, Chuuk, Federated States of Micronesia, Caroline Islands, Micronesia, Pacific Ocean, Pacific

Diver and Hawksbill Turtle (Eretmochelys imbriocota), Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with underwater photographer in background, Cayman Brac, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with boat silouhette above, Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over reef with scuba diver, Little Cayman Island, Cayman Island, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with diver in background, Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef Little Cayman Island, Cayman Islands, Caribbean

The Deep, Europe's deepest aquarium, Hull, England, United Kingdom, Europe

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with underwater photographer in background, Cayman Brac, Cayman Islands, Caribbean

Green sea turtle (Chelonia mydas) head detail, Kailua-Kona, Hawaii, United States of America, Pacific

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef, Little Cayman Island, Cayman Island, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef Little Cayman Island, Cayman Islands, Caribbean

Green sea turtle (Chelonia mydas) head detail, Kailua-Kona, Hawaii, United States of America, Pacific

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef, Little Cayman Island, Cayman Island, Caribbean

Diver and Hawksbill Turtle (Eretmochelys imbriocota), Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with diver in background, Little Cayman Island, Cayman Islands, Caribbean

The Deep, Europe's deepest aquarium, Hull, England, United Kingdom, Europe

Hawksbill Turtle (Eretmochelys imbriocota) swimming upwards along tropical coral reef, Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef Little Cayman Island, Cayman Islands, Caribbean

Hawksbill Turtle (Eretmochelys imbriocota), swimming over coral reef with boat silouhette above, Little Cayman Island, Cayman Islands, Caribbean

Olive ridley turtle hatchling, Lepidochelys olivacea, Costa do Sauipe, Bahia, Brazil (South Atlantic)

Green sea turtles hatching, Chelonia mydas, Fernando de Noronha, Pernambuco, Brazil.

Crab preying on dead portuguese man-of-war, Physalia physalis, Praia do Forte, Bahia, Brazil (South Atlantic)

Parrotfish sleeping, Sparisoma sp., head detail, Ponta da Sapata, Fernando de Noronha national marine sanctuary, Pernambuco, Brazil (S. Atlantic)

Olive ridley turtle hatchling, Lepidochelys olivacea, Costa do Sauipe, Bahia, Brazil (South Atlantic)

Painted frogfish, Antennarius pictus, white phase, Sabang wreck, Puerto Galera, Mindoro, Philippines.

Electric eel, Electrophorus electricus; this air-breathing freshwater fish can deliver an electric shock up to 650 volts and naturally occurs in the Amazon river basins of South America including Brazil and Guyanas; photo taken in captivity.

Needle cuttlefish, Sepia aculeata, front view at night, Dumaguete, Negros Island, Philippines.

Nudibranch, Atlantis house reef, Dumaguete, Negros Island, Philippines.

Feather star on sea fan, and scalefin anthias, Pseudanthias squamipinnis, Kilima steps, Puerto Galera, Mindoro, Philippines.

Hermit crab, Coenobita perlatus, Bird I., Mili, Marshall Islands (N. Pacific).

Wave breaking over shallow coral reef, Ailuk atoll, Marshall Islands, Pacific

Stripe-leg spiny lobster, Panulirus femoristriga, eye and rostrum detail, Short drop-off, Palau, Micronesia.

Soft coral, Dendronephthya sp., Lapus Lapus Island marine park, Malapascua, Cebu, Philippines.

Emperor angelfish, Pomacanthus imperator, Namu atoll, Marshall Islands (N. Pacific).

Clark's anemonefish, Amphiprion clarkii, unusual color variant, male, Dauin, Negros, Philippines..

Snowflake moray eel, Echidna nebulosa, scavenging in seagrass beds, Dumaguete, Negros, Philippines, Visayan sea.

Bigfin reef squid, Sepioteuthis lessoniana, schooling, Rongelap, Marshall Islands, Micronesia

Starry night octopus, Octopus luteus, foraging on coral reef at night, Malapascua, Cebu, Philippines, Visayan Sea.

Common lionfish, Pterois volitans, blends in with a variety of soft corals and sponges, Cars, Dumaguete, Negros Island, Philippines.

Juvenile striped catfish, Plotosus lineatus, schooling and feeding on sandy bottom, Puerto Galera, Mindoro, Philippines.

Thousands of scalefin anthias, Pseudanthias squamipinnis, hover over corals and barrel sponge, Puerto Galera, Mindoro, Philippines.

Short-tailed pipefish, Trachyrhamphus bicoarctatus, Masaplod, Dumaguete, Negros Island, Philippines..

Spiral coral, Cirrhipathes spiralis, Dungan wall, Puerto Galera, Mindoro, Philippines.

Pink hydrocoral (lace coral), Stylaster sp., Namu atoll, Marshall Islands (N. Pacific).

Emperor shrimp, Periclimenes imperator, next to gills of spanish dancer, Hexabranchus sanguineus, night, Puerto Galera, Mindoro, Philippines.

Family of false clown anemone fish, Amphiprion ocellaris, seeking refuge in sea anemone, Masaplod, Dumaguete, Negros Island, Philippines.

Aggregation of pyramid butterflyfish, Hemitaurichthys polylepis, Siaes drop-off, Palau, Micronesia.

Pleurobranch sidegill slug, Berthella martensi, mantle detail, Puerto Galera, Mindoro, Philippines.

Mandarinfish, Synchiropus splendidus, male, Malapascua, Cebu, Philippines, Visayan Sea.

Map puffer, Arothron mappa, Skin texture detail, Dumaguete, Negros, Philippines, Visayan sea.

Nudibranch, Chromodoris magnifica, Dumaguete, Negros Island, Philippines.

Over under image of coral reef, Acropora spp., and trees at Majikin Island, Namu atoll, Marshall Islands (N. Pacific).

Bottlenose dolphin, Tursiops truncatus, Oahu, Hawaii (N. Pacific).

Bluefin trevally, Caranx melampygus, Ailuk atoll, Marshall Islands, Pacific

Juvenile and adult pink anemonefish in sea anemone, Amphiprion perideraion, Fila Reef, Port Vila, Vanuatu (S. Pacific).

Bigfin reef squid, Sepioteuthis lessoniana, schooling, Rongelap, Marshall Islands, Micronesia

Over under image of coral reef, Acropora spp., and trees at Majikin Island, Namu atoll, Marshall Islands (N. Pacific).

Orange-finned anemonefish, Amphiprion chrysopterus, and Merten's sea anemone, Stichodactyla mertensii, Namu atoll, Marshall Islands (N. Pacific).

Saddled butterflyfish, Chaetodon ephippium, Namu atoll, Marshall Islands (N. Pacific).

Beaked Whale stranded on coral reef during low tide, Mesoplodon sp., Mili, Marshall Islands (N. Pacific)..

Jellyfish, Mastigias sp., Palau, Micronesia.

Swimming crab, Charybdis acutifrons, Gato Island, Cebu, Philippines.

Split image of Smallspotted dart, Trachinotus baillonii, swimming along the sandy shore at dusk, Rongelap, Marshall Islands, Micronesia

Fan coral, Subergorgia sp., and diver silhouette against he sun, Namu atoll, Marshall Islands (N. Pacific).

Split image of lush vegetation and free diver observing lettuce coral, Turbinaria reniformis, next to cave entrance, Palau, Micronesia.

Regal angelfish, Pygoplites diacanthus, Hideaway island, Port Vila, Vanuatu.

Ornate ghost pipefish, Solenostomus paradoxus, Dumaguete, Negros Island, Philippines.