Half of all marine life has been lost in the last 40 years. By 2050 there will be more plastic in the sea than fish. The way the ocean operates is different to how we thought of it 100 years ago. We can no longer think of it as a place of limitless resources, a dumping ground, immune to change or decline. Blue takes us on a provocative journey into the ocean realm, witnessing a critical moment in time when the marine world is on a precipice. Featuring passionate advocates for ocean preservation, blue takes us into their world where the story of our changing ocean is unfolding. We meet those who are defending habitats, campaigning for smarter fishing, combating marine pollution and fighting for the protection of keystone species. This feature documentary comes at a time when we are making critical decisions that will decide the legacy we leave for generations to come. Blue shows us there is a way forward and the time to act is now.