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

The series was debuted on 29 October 2017 and simulcast at BBC One, BBC One HD and BBC Earth channel, making it the first series to premiere on the same day in the United Kingdom, Nordic regions, European countries and in Asia.

The series was announced by the BBC in 2013 with the working title Oceans, but the title was later changed to Blue Planet II on 19 February 2017. Filming took place over a course of more than four years; involving 125 expeditions across 39 countries and produced more than 6,000 hours of underwater dive footage from over an estimated 4000 dives.

The premiere of the series took place at Bristol's Cinema de Lux on 11 October 2017, with special guest appearance by Attenborough alongside with the producers and wildlife experts. Bristol has been the global home of BBC's Natural History programme making for the past 60 years.The series was first broadcast on 29 October 2017 (from 20:00 GMT to 21:00 GMT) at BBC One and BBC One HD. Each of the seven episodes included a 10-minute making-of documentary called Into the Blue.The previous week's episode was repeated in an earlier time slot the following Sunday.

The BBC pre-sold the series to several overseas broadcasters, including Canada (Blue Ant Media’s licensed channel for BBC Earth), Australia (Channel Nine) and New Zealand (TVNZ), to Europe with Denmark (DR), Netherlands (NPO), Sweden (SVT), Spain (Telefonica’s BBC Earth block), Discovery Channel for Latin America and co-production partnerships with BBC America, Germany’s WDR, France Télévisions and China's Tencent. The series was eventually sold to more than 30 countries.

The series is currently broadcast internationally on BBC Earth channel, and also commercial television channels in various countries, besides. The series debuted in Nordic regions and other European countries on 29 October 2017. In Asia, the series began to premiere on each early Monday (from 04:05 SGT to 05:05 SGT) starting from 30 October 2017, the episode was then repeated on following each Tuesday evening (from 20:00 SGT).In Poland, the series premiered on 16 November 2017.

In China, the premiere of the series took place at Shanghai's East China Normal University on 27 October 2017, with special guest appearance by the producer Orla Doherty with Michael Gunton, the executive producer of Planet Earth II. The series is streaming broadcast at Tencent's QQLive from 30 October 2017, with episodes updating each Monday (18:00 CST). It would also be broadcast on the state owned China Central Television’s documentary channel, CCTV-9, with episodes airing each Monday (from 21:00 CST) starting from 6 November 2017.

In the Netherlands, the series is airing on the Dutch channel NPO 1, with episodes airing each Thursday from 28 December 2017. In Belgium, the series will be aired on the Flemish channel Canvas, with episodes airing each Saturday starting from 2 January 2018.

As for Australia, the series will be premiered at Nine Network in February 2018. In New Zealand, it premiered on 12 November 2017 at TVNZ 1.