Alex Mustard / Spinner dolphin (Stenella longirostris) pod socialising close to surface. Fury Shoal, Sataya Reef, Marsa Alam, Egypt.

Tony Wu / Sperm whale (Physeter macrocephalus), ten swimming together in gathering of more than 50 individuals. Whales with flatulence and defecating. Sri Lanka.

Alex Mustard / Pod of False killer whales (Pseudorca crassidens) swimming beneath the surface of the ocean. Indian Ocean, off Sri Lanka.

Franco Banfi / Sleeping sperm whale, (Physeter macrocephalus) Dominica, Caribbean Sea, Atlantic Ocean.

Franco Banfi / Sperm whale, (Physeter macrocephalus) Dominica, Caribbean Sea, Atlantic Ocean.

Franco Banfi / Pod of sperm whale socializing, (Physeter macrocephalus), Dominica, Caribbean Sea, Atlantic Ocean.

Espen Bergersen / Long-finned pilot whale (Globicephala melas). Kvaloya, Norway.

Shane Gross / Bottlenose dolphin (Tursiops truncatus) underwater playing in the shallows off Eleuthera, Bahamas.

Shane Gross / Bottlenose dolphin (Tursiops truncatus) underwater rubbing herself on a sponge off Eleuthera, Bahamas.

Espen Bergersen / Sperm whale {Physeter macrocephalus} showint tail fluke as it dives. Photographed just before midnight. 22 nautical miles northwest of Andenes, Northern Norway. July

Espen Bergersen / Killer whale / orca (Orcinus orca). Spyhopping very close, showing eye. Kvanangen, Troms, Norway. November

Espen Bergersen / Killer whales / orcas (Orcinus orca) and boat in background. Kvanangen, Troms, Norway. November