Pascal Kobeh / Giant clam (Tridacna) on 'Lotus' artificial reef, built in 2001 with a steel frame using mild electric currents to encourage coral growth, with diver in the background. Vabbinfaru Island in North Male...

Doug Perrine / Rough-toothed dolphins (Steno bredanensis) Keauhou, Kona, Hawaii, USA, Central Pacific Ocean.

Franco Banfi / Scuba diver and Manta ray (Manta birostris), San Benedicto, Revillagigedo (Socorro) Islands, Mexico, East Pacific Ocean. Model released.

Michael Pitts / Diver on the wreck of the US Submarine tender USS Macaw, sunk in the World War II due to a navigation error, Midway atoll, Pacific Ocean. Model released.

Alex Mustard / Circular fisheye photograph of a colourful coral reef with silhouetted diver, East End, Grand Cayman, Cayman Islands, British West Indies. Caribbean Sea. Model released

Alex Mustard / A diver exploring a coral reef with formation of brown tube sponges (Agelas conifera) red rope sponges (Amphimedon compressa) and deepwater sea fans (Iciligorgia nodulifera) East End, Grand Cayman, Ca...

Alex Mustard / Diver swimming through dense school of Silversides (Atherinidae) inside a coral cavern, Grand Cayman, Cayman Islands, British West Indies, Caribbean Sea. Model released

Jeff Rotman / Looking down on the shipwreck of the small freighter 'Ora Verde' that sank in 1980, Grand Cayman Island, Caribbean Sea Model released.

Fred Bavendam / Pacific Giant Octopus (Enteroctopus dofleini) squirting ink in defense as it jets away, Quadra Island, British Columbia, Canada

Fred Bavendam / Pacific Giant Octopus (Enteroctopus dofleini) female guarding her eggs, Quadra Island, British Columbia, Canada

Fred Bavendam / Pacific Giant Octopus (Enteroctopus dofleini) flaring out its arms as it settles to the ocean bottom after swimming, Quadra Island, British Columbia, Canada

Fred Bavendam / Pacific Giant Octopus (Enteroctopus dofleini) flaring out its arms as it prepares to drop to the ocean bottom after swimming, Quadra Island, British Columbia, Canada