The '''harbour porpoise''' (''Phocoena phocoena'') is one of seveneight extant [[species]] of [[porpoise]]. It is one of the smallest species of [[cetacean]]. As its name implies, it stays close to coastal areas or river estuaries, and as such, is the most familiar porpoise to [[whale-watching|whale watchers]]. This porpoise often ventures up rivers, and has been seen hundreds of kilometres from the sea. The harbour porpoise may be [[Monotypic taxon|polytypic]], with geographically distinct populations representing distinct races: ''P. p. phocoena'' in the North Atlantic and West Africa, ''P. p. relicta'' in the Black Sea and Sea of Azov, an unnamed population in the northwestern Pacific and ''P. p. vomerina'' in the northeastern Pacific.<ref name=shirihai>{{cite book|author1=Shirihai, Hadoram |author2=Jarrett, Brett |title= ''Whales, Dolphins and Seals - A Field Guide to the Marine Mammals of the World''|year=2006|publisher=A&C Black Publishers |isbn=978-0-7136-7037-0}}</ref>
