Nuno Sa / Long snouted seahorse (Hippocampus guttulatus) in captive breeding laboratory at University of Algarve, Portugal. June 2010. Overall winner of the Underwater Photographer of the Year competition 2015.

Juergen Freund / Gorgonian fan coral (Gorgonaceae) in the shallow mangroves, split level. North Raja Ampat, West Papua, Indonesia. Second Place in the Portfolio Award of the Terre Sauvage Nature Images Awards Competit...

Solvin Zankl / Deepsea Viperfish (Chauliodus sloani) specimen from the North Atlantic near the North West of Spain, at a depth of 560-580m.

Solvin Zankl / Deepsea Isopod (Glyptonotus antarcticus) from Antarctic Ocean at a depth of 231m.

Solvin Zankl / Sargassum fish (Histrio histrio) in Broad-toothed gulfweed (Sargassum fluitans) Sargassum Community. Sargasso Sea, Bermuda

Solvin Zankl / Sargassumfish (Histrio histrio) swimming near Broad-toothed gulfweed (Sargassum fluitans) Sargassum Community. Sargasso Sea, Bermuda.

Franco Banfi / Walrus (Odobenus rosmarus) hauled out in shallow water, Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Franco Banfi / Walrus (Odobenus rosmarus) male and female, hauled out in shallow water, Spitsbergen, Svalbard Archipelago, Norway, Arctic Ocean. July.

Staffan Widstrand / Atlantic Walrus (Odobenus rosmarus) at surface, Svalbard, Norway, Arctic, September

Chris & Monique Fallows / Long-beaked common dolphin (Delphinus capensis) school off the coast of False Bay, with dramatic sky, South Africa, May.

Chris & Monique Fallows / Long-beaked common dolphin (Delphinus capensis) school porpoising, False Bay, South Africa

Juergen Freund / Bigfin reef squid (Sepioteuthis lessoniana) blurred motion photograph, Kimbe Bay, West New Britain, Papua New Guinea.