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. We can no longer think of the ocean as a place of limitless resources, a dumping ground, immune to change or decline. This provocative journey into the undersea realm captures 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. At a time when we are making critical decisions that will impact generations to come, this feature documentary shows us there is a way forward and that the time to act is now.