Alex Mustard / Brandt's cormorant (Phalacrocorax penicillatus) hunts for a meal in a school of Pacific chub mackerel (Scomber japonicus) beneath an oil rig. Eureka Rig, Los Angeles, California, USA, September

Alex Mustard / Brandt's cormorant (Phalacrocorax penicillatus) hunts for a meal in a school of Pacific chub mackerel (Scomber japonicus), beneath an oil rig. Eureka Rig, Los Angeles, California, United States of Ame...

Alex Mustard / Diver swimming over the stern gun turret of the 330ft long Russian frigate 356, the "MV Keith Tibbetts". The ship was built in 1984 and sunk in 1996. Buccaneer Reef, Cayman Brac, Cayman Islands. Carib...

Pascal Kobeh / Divers are setting up concrete reef balls to build an artificial reef, Philippines, Sulu Sea. August 2014.

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...

Juergen Freund / Non-diver tourists surrounded by fish, trying out the sea walker from the Sunlover Pontoon, Great Barrier Reef, Queenland, Australia, November 2012

Franco Banfi / Person well dressed for cold temperatures, Arctic circle Dive Center, White Sea, Karelia, northern Russia. No release available.

Franco Banfi / Scuba diver with special head hood for cold water diving, Arctic circle Dive Center, White Sea, Karelia, Northern Russia, April 2009. No release available.

Neil Lucas / Camerman Doug Allan at frozen water surface of drilled ice hole, BBC film crew, McMurdo Sound, Ross Sea, Antarctica, November 2008

Jeff Rotman / Diver holds 20 kilo Northern / American Lobster (Homarus americanus) with claws open, demonstrating aggressive behavior, New England, USA, North Atlantic Ocean. Model released Model released.

Wild Wonders of Europe / Lundgren / Photographer, Magnus Lundgren, in diving gear with photography equipment, Saltstraumen, Bod, Norway, October 2008, photographed by Klas Malmberg, model released

Mark Brownlow / Rebreather instructor Ian Thomas and cameraman Didier Noirot prepare to dive under the ice, Lake Baikal, world's deepest and oldest (and largest by volume) freshwater lake, Siberia, Russia. BBC Plane...