So while this is environmental film-making at its most powerful — at times, it comes at you like a sledgehammer blow — crucially, it finds cause for optimism.

Attenborough makes an incredibly convincing argument that this is the only way forward.

A gorgeously-shot film that celebrates the unique beauty and diversity that comes from dipping our heads beneath the surface of the water -- while also addressing the state of the world’s seas. It’s dire.

Attenborough and his collaborators focus on how [the oceans] can be saved. His passion for the subject makes what could have been a preachy project into something fascinating.