Ashley Cooper / Young Basking shark (Cetorhinus maximus) swimming close to shore near a couple fishing off the rocks at Porthcurno, Cornwall, UK. June 2010

Ashley Cooper / Commerson's Dolphin (Cephalorhynchus commersonii) swimming round a ship off the Falkland Islands. February 2014

Ashley Cooper / Commerson's Dolphin (Cephalorhynchus commersonii) swimming round a ship off the Falkland Islands. February 2014

Ashley Cooper / Commerson's Dolphin (Cephalorhynchus commersonii) swimming round a ship off the Falkland Islands. February 2014

David Pattyn / Humpback whales (Megaptera novaeangliae), two, one with tail emerging from the water as it dives, the other showing fin. Anjajavy Private Reserve in background. Mozambique Channel, Indian Ocean, north...

Graham Eaton / Blacktip Reef Shark (Carcharhinus melanopterus) in clear shallow waters, rear view, Maldives, Indian Ocean.

Tony Wu / Humpback whale (Megaptera novaeangliae) adult female in foreground, with her male calf and their escort behind her. Vava'u, Tonga, South Pacific.

Espen Bergersen / Humpback whale (Megaptera novaeangliae) and Killer whales (Orcinus orca) most likely feeding on herring, off coast of Kvaloya, Troms, Norway, December

Espen Bergersen / Humpback whale (Megaptera novaeangliae) lobtailing / tail slapping on surface, Killer whale (Orcinus orca) in foreground, Kvaloya, Troms, Norway, October

Franco Banfi / Sperm whales (Physeter macrocephalus) surfacing showing tail and dorsal fin, Dominica, Caribbean Sea, Atlantic Ocean. Vulnerable species.

Tony Wu / Bicolor parrotfish (Cetoscarus bicolor) juvenile with tail fin flared open, Kokopo, Little Pigeon Island, Papua New Guinea

Wild Wonders of Europe / Widstrand / Humpback whale (Megaptera novaeangliae) surfacing with fishing rope tangled around tail fluke causing wound, surfacing Orca (Orcinus orca) behind, Senja, Troms County, Norway, Scandinavia, January. Ce...