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

Alex Mustard / Oceanic whitetip shark (Carcharhinus longimanus) swimming close to surface. Brothers Islands, Egypt.

Alex Mustard / Two female Common seahorses (Hippocampus kuda) fighting over territory on the seabed. The brief fight was preceeded by a ritualised, synchronised parade. Bitung, North Sulawesi, Indonesia. Lembeh Stra...

Alex Mustard / Common seahorse (Hippocampus kuda) female wrapping her prehensile tail around piece of wood on the seabed. Bitung, North Sulawesi, Indonesia. Lembeh Strait, Molucca Sea.

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

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 / 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

Espen Bergersen / Killer whales / orcas (Orcinus orca). Spyhopping. Kvaloya, Troms, Norway November

Espen Bergersen / Killer whales / orcas (Orcinus orca). Spyhopping. Kvaloya, Troms, Norway October