When does Blue Planet II return?

Blue Planet II is a 2017 British nature documentary series on marine life produced by the BBC Natural History Unit. It is narrated and presented by the naturalist Sir David Attenborough. The series was announced in 2013 and was filmed over four years in 39 countries, in more than 125 international trips. The score was composed by Hans Zimmer, Jacob Shea and David Fleming for the series. It had the highest viewing figures of any television programme in the UK in 2017.