David Fleetham / A Green sea turtle (Chelonia mydas) at surface to breathe, over shallow reef, Hawaii USA.

David Fleetham / Aerial view of airplane shadow over shallow water near sand bar, with boats in the water. Sumion Island, Cebu, Philippines.

Alex Mustard / Portrait of a Bigfin reef squid (Sepioteuthis lessoniana) at night above a coral reef. Gam Island, Raja Ampat, West Papua, Indonesia. Dampier Strait, Tropical West Pacific Ocean.

David Fleetham / Endangered Green sea turtle (Chelonia mydas) stretches neck to be cleaned by Yellow tangs (Zebrasoma flavescens) and Goldring tangs (Ctenochaetus strigosus), North Pacific, Hawaii, USA.

Doug Perrine / Blue marlin (Makaira nigricans) Vava'u, Kingdom of Tonga, South Pacific

Tony Wu / Female Northern pygmy squid (Idiosepius paradoxus) depositing eggs on a blade of eelgrass (Zostera marina), Yamaguchi Prefecture, Japan.

Tony Wu / Female Northern pygmy squid (Idiosepius paradoxus) preparing to lay another egg on a blade of eelgrass (Zostera marina), Yamaguchi Prefecture, Japan.

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) yearling pup playing with own air bubbles in shallows, Gardner Islet, Espanola Island, Galapagos, Ecuador

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) pups playing at sunrise, Puerto Egas, Santiago Island, Galapagos, Ecuador

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) female and male on red volcanic beach, Rabida Island, Galapagos, Ecuador

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) female resting in shallows, Bainbridge Islets, Galapagos, Ecuador

Tui De Roy / Galapagos sea lion (Zalophus wollebaeki) pups playing in shallows, Sombrero Chino, Santiago Island, Galapagos, Ecuador

Claudio Contreras / Guadalupe fur seal (Arctocephalus townsendi) male fighting, Guadalupe Island Biosphere Reserve, off the coast of Baja California, Mexico, April

David Fleetham / Day octopus (Octopus cyanea) female, in mid-water, Hawaii.

David Fleetham / Day octopus (Octopus cyanea) hiding in the reef, Hawaii.

Andy Murch / Smooth hammerhead shark (Sphyrna zygaena). Cabo San Lucas, Baja California Sur, Mexico.

Andy Murch / Scoophead shark (Sphyrna media), released specimen. Isla Chepillo, Rio Bayano, Panama.

Andy Murch / Red stingray (Hemitrygon akajei) with Banded houndshark (Triakis scyllium) group and smaller fish in background. Chiba Prefecture, Honshu, Japan. September.

Andy Murch / Rasptail skate (Raja velezi) resting on sea floor. La Paz Bay, Baja California Sur, Mexico.

Andy Murch / Banded houndshark (Triakis scyllium) group above sea floor. Chiba Prefecture, Honshu, Japan. October.

David Fleetham / Close up at the dental plates of Three color parrotfish (Scarus tricolor) as it comes in for a bite of hard coral, Fiji.

Tony Wu / Crab-eye goby (Signigobius biocellatus), mimics crab with eye-spot markings on dorsal fins and back and forth movement. Loloata Island, Papua New Guinea.

Tony Wu / Harlequin mantis shrimp (Odontodactylus scyllarus), close up of compound eyes. Lembeh Strait, North Sulawesi, Indonesia.

Alex Mustard / Saddleback anemonefish (Amphiprion polymnus) barks a warning as it guards a clutch of developing eggs (beneath it) laid on a small stone, below a fold in its home, a Haddon's sea anemone (Stichoda...

Mark Carwardine / Fin whale (Balaenoptera physalus), two feeding, aerial view. Baja California, Mexico. March.

Mark Carwardine / Spinetail devil ray (Mobula mobular), four with rays of light and sparkle of sun on water, aerial view. Sea of Cortez, Baja California, Mexico. March.

Magnus Lundgren / Juvenile Wunderpus octopus (Wunderpus photogenicus) Balayan Bay, off Anilao, Batangas, Philippines, Pacific Ocean.

Tony Wu / Male Korean seahorse (Hippocampus haema) giving birth. Kumamoto Prefecture, Kyushu, Japan.

Danny Green / Sea otter (Enhydra lutris) female and pup playing. Alaska, USA, February.

Danny Green / Sea otter (Enhydra lutris) female and pup. Alaska, USA, February.

Brandon Cole / Hawksbill sea turtle (Eretmochelys imbricata).French Polynesia, Pacific Ocean.

Brandon Cole / Hawksbill sea turtle (Eretmochelys imbricata) French Polynesia, Pacific Ocean.

Brandon Cole / Grey reef sharks (Carcharhinus amblyrhynchos), schooling, French Polynesia, Pacific Ocean.

Brandon Cole / Crescent-tail bigeyes (Priacanthus hamrur), and Grey reef sharks (Carcharhinus amblyrhynchos). French Polynesia, Pacific Ocean.

Brandon Cole / Orca whale (Orcinus orca) spyhopping, British Columbia, Canada, Pacific Ocean.

Brandon Cole / Orca whales (Orcinus orca), three adult male resident killer whales travelling together at sunset. British Columbia, Canada, Pacific Ocean.

Brandon Cole / Silky shark (Carcharhinus falciformis), feeding on small fish, juvenile Bigeye jacks (Caranx sexfasciatus) in baitball. Baja, Mexico, Pacific Ocean.

Brandon Cole / Yellowfin tuna (Thunnus albacores) Baja, Mexico, Pacific Ocean.

Brandon Cole / Steel pompano (Trachinotus stilbe) fish swimming under stormy seas at Roca Redonda offshore Baja, Mexico, Pacific Ocean.

Brandon Cole / Golden jellyfish (Mastigias papua),Jellyfish Lake, Palau.

Brandon Cole / Golden jellyfish (Mastigias papua), Jellyfish Lake, Palau.

Brandon Cole / Golden jellyfish (Mastigias papua), Jellyfish Lake, Palau.

Brandon Cole / Diver with Golden jellyfish (Mastigias papua), Jellyfish Lake, Palau. Model released.

Tui De Roy / Galapagos sea lions (Zalophus wollebaeki) sub adult males playing with starfish, Mosquera Islet, Galapagos.

Doug Perrine / Yellowfin tuna (Thunnus albacares) and Pantropical spotted dolphins (Stenella attenuata) feeding on bait fish, Pacific Ocean off southern Costa Rica.

Doug Perrine / Humpback whale (Megaptera novaeangliae) breaching as calf splashes down after a breach; windmills in background produce renewable energy; Hawaii Humpback Whale National Marine Sanctuary, Maui, Hawaii.