The Harbour Porpoise is one of the smallest mammals of the sea, although it can grow up to nearly two metres in length and can weigh up to ninety kilogrammes. It also known as the Common Porpoise and can be seen around the English coast and in the inshore waters around the north Devon coast. It is the only porpoise found in our waters.

Some observers mistake the Harbour Porpoise for the small Bottle-nosed Dolphin. The Harbour Porpoise has a blunt head and no distinct beak, whereas the Bottle-nosed Dolphin has a long beak. It has a black or deep grey body on top and a light grey or white body below. It has flippers at the side of its body and a triangular-shaped fin on its back. This fin is called the ‘dorsal’ fin and is about twenty centimetres tall. The Harbour Porpoise has a mouth that is slightly upturned and teeth that are spade-shaped.

Harbour Porpoises are relatively slow swimmers that very rarely jump out of the water. They are usually seen in pairs or in small groups of five to ten and are difficult to observe because they swim with most parts of their bodies under the surface of the water.