Peter Bassett / Male Southern elephant seal (Mirounga leonina) shifting position on a beach, surrounded by females, almost crushing a pup, Gold Harbour, South Georgia.Gold Harbour, South Georgia.

Ingo Arndt / King Penguin (Aptenodytes patagonicus) young chick, Jason Harbour, South Georgia Island, February

David Tipling / King penguins (Aptenodytes patagonicus) pair interacting, part of courtship, Gold Harbour South Georgia, January

Alex Mustard / Harbour seal (Phoca vitulina) in the kelp forest (Macrocystis pyrifera). Santa Barbara Island, Channel Islands. Los Angeles, California, United States of America. North East Pacific Ocean.

Brent Stephenson / Sunset off Scott Island, with floating pieces of sea ice, Scott Inlet, Baffin Island, Canadian Arctic, August 2015.

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

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

Gavin Hellier / Timelapse from day to night overlooking Hong Kong Island towards Victoria Peak, Victoria Harbour and the Financial District, Hong Kong, China, 2011.

Franco Banfi / View of Procida, the small harbour of Corricella, island near Ischia Island, Italy, Tyrrhenian Sea, Mediterranean

Franco Banfi,Franco Banfi / Local man looking down at shoal of Bigeye scad (Selar crumenophthalmus) Waigeo island, Raja Ampat, Irian Jaya, West Papua, Indonesia, Pacific Ocean

Terry Whittaker / 2020VISION / Common seals (Phoca vitulina) hauled out on saltmarsh, Wallasea Wild Coast Project, RSPB Greater Thames Futurescapes Project, Wallasea Island, Essex, England, UK, October

Sven Zacek / Lagoons and small harbour on the island of Hiiumaa. Estonia, Europe, April 2011.