Sir David Attenborough reveals how his lifetime has coincided with the great age of ocean discovery. Through spectacular sequences featuring coral reefs, kelp forests and the open ocean, Attenborough shares why a healthy ocean keeps the entire planet stable and flourishing. Stunning, immersive cinematography showcases the wonder of life under the seas and exposes the realities and challenges facing our ocean as never-before-seen, from destructive fishing techniques to mass coral reef bleaching. Yet the story is one of optimism, with Attenborough pointing to inspirational stories from around the world to deliver his greatest message: the ocean can recover to a glory beyond anything anyone alive has ever seen.