Shane Gross / Flying fish (Exocoetidae) in Sargasso Sea, Atlantic Ocean.

Nick Hawkins / Atlantic bluefin tuna (Thunnus thynnus) off Antigonish, Nova Scotia, Canada. October .

David Fleetham / Humpback whale (Megaptera novaeangliae), mother and calf swimming just below surface in front of the West Maui Mountains. South of Lahaina, West Maui, Hawaii.

Jordi Chias / Split level view of Blue shark (Prionace glauca) at surface at sunset, Azores Islands, Portugal, Atlantic Ocean

Claudio Contreras / Whale shark (Rhincodon typus) feeding view of tail, Isla Mujeres, Caribbean Sea, Mexico, August. Vulnerable species.

Richard Robinson / Blue shark (Prionace glauca) worked from below with rays of sun, off the coast of Hawke's Bay, New Zealand, February.

Frederique Olivier / Adelie penguins (Pygoscelis adeliae) wide angle portrait of two with larger group in background, Antarctica.

Richard Robinson / Hector's dolphin (Cephalorhynchus hectori) Akaroa Harbour, South Island, New Zealand, November. Editorial use only.

Alex Mustard / Portrait of male Scalefin anthias (Pseudanthias squamipinnis) swimming in open water, to feed on plankton. Ras Katy, Sinai, Egypt. Gulf of Aqaba, Red Sea.

Chris & Monique Fallows / Indo Pacific Sailfish (Istiophorus platypterus) feeding on sardines, Isla Mujeres, Mexico.

Cheryl-Samantha Owen / Southern Rockhopper penguin (Eudyptes chrysocome) tame bird 'Rocky' used for educational purposes, Southern African Foundation for the Conservation of Coastal Birds (SANCCOB), Cape Town, South Africa....

Jeff Rotman / Pectoral fin of a Steepheaded parrotfish (Chlororus gibbus) in the Red Sea, Egypt.