Blue Planet II is a 2017 British nature documentary series on marine life produced by the BBC Natural History Unit. Like its predecessor, The Blue Planet (2001), it is narrated and presented by the naturalist Sir David Attenborough.

A nature documentary or wildlife documentary is a genre of documentary film or series about animals, plants, or other non-human living creatures. Nature documentaries usually concentrate on video taken in the subject's natural habitat, but often including footage of trained and captive animals, too. Sometimes they are about wildlife or ecosystems in relationship to human beings. Such programmes are most frequently made for television, particularly for public broadcasting channels, but some are also made for the cinema. The proliferation of this genre occurred almost simultaneously alongside the production of similar television series which is distributed across the world.