Alex Mustard / A fisherman swims down to touch the statue of Christ Of The Abyss (Cristo degli abissi) for good fortune, in the Marine Protected Area of Portofino (Area Marina Protetta, Portofino), Liguria, Italy. M...

Robert Smith / Diver exploring a freshwater Limestone sinkhole / Cenote called 'The Pit' - a traverse to 'The Blue Abyss' with stalactites and stalagmites, Tulum, Quintana Roo, Mexico, September 2008. Model released

Norbert Wu / Humpback Anglerfish (Melanocetus johnsoni) deep sea species cleared and stained for show, bone (Red) and cartilage (Blue)

Norbert Wu / Humpback Anglerfish (Melanocetus johnsoni) deep sea species cleared and stained for show, bone (Red) and cartilage (Blue)

Michel Roggo / Anhumas Abyss a cave with freshwater lake, reflections of blue and green caused by magnezium and limestone in the cavern rocks, Bonito area, Serra da Bodoquena (Bodoquena Mountain Range), Mato Grosso...

Michael Pitts,Michael Pitts / Presenter Mike De Gruy and Cameraman Bob Cranston on BBC filming assignment for 'Live From The Abyss' Cocos Island 2003

Robert Smith / Diver exploring a freshwater Limestone sinkhole / Cenote called 'The Pit' - a traverse to 'The Blue Abyss' with stalactites and stalagmites, Tulum, Quintana Roo, Mexico, September 2008

Robert Smith / Diver exploring a freshwater Limestone sinkhole / Cenote called 'The Pit' - a traverse to 'The Blue Abyss' with stalactites and stalagmites, Tulum, Quintana Roo, Mexico, September 2008

Norbert Wu / Slender Hatchetfish (Argyropelecus affinis) cleared and stained to show bones (Red) and cartilage (Blue) deep sea

Norbert Wu / Fangtooth (Anoplogaster cornuta) cleared and stained to show bones (Red) and cartilage (Blue) deep sea

Norbert Wu / Black Sea Dragon (Idiacanthus antrostomus) cleared and stained to show bone in red and cartilage in blue, deep sea

Norbert Wu / Slender Hatchetfish (Argyropelecus affinis) cleared and stained to show bones (Red) and cartilage (Blue) deep sea