Eleanor Mortimer's How Deep Is Your Love operates like a nature documentary that accidentally stumbled into a policy briefing and decided to stay for tea. The surface layer — and it is genuinely delightful — is a portrait of marine biologists doing the most joyful work imaginable: pulling never-before-seen creatures from 5,000 metres down and naming them things like the Psychedelic Elvis Worm because the formal Latin taxonomy will take years to catch up. The wonderstruck faces of scientists clapping eyes on organisms no human has ever seen are the film's emotional engine, and Mortimer's playful voiceover keeps the whole thing light without becoming condescending. The science here is legitimately staggering. The ship's robot takes four hours to reach the ocean floor. Eighty percent of what comes back up is new to science. Ninety percent of deep-sea life hasn't been named. These aren't rhetorical flourishes — they're the actual state of knowledge, which makes the film's central tension more unsettling than any horror film could manage: we are considering mining a world we have not yet met. The deep-sea nodules are where the documentary finds its spine. Potato-sized lumps rich in the metals that power batteries and electronics, formed over millions of years, coverable by industrial machinery in a season. Mortimer doesn't editorialize heavily — she lets a frustrating, inconclusive debate at the International Seabed Authority do the work. It's the right call. The scene is maddening precisely because it's accurate: a bureaucratic body inching toward a decision about something irreversible while the scientists who actually know what lives down there watch from the gallery. The film's weakness is also its strength: it's gentle to a fault. Mortimer seems constitutionally unwilling to land a punch, and the mining threat, while present, never quite achieves the dramatic weight the subject deserves. The film acknowledges it doesn't yet know the environmental impact of mining — which is honest — but then doesn't push hard on who is pushing for mining anyway, what companies are positioned to profit, or what 'permitting' at the International Seabed Authority actually looks like in practice. The result is a film that raises the alarm without quite ringing the bell. But there's something to be said for a documentary that trusts wonder to do political work. The implicit argument — that we should probably know what lives somewhere before we industrialize it — doesn't need a villain monologue to land. Watching a scientist gasp at a bioluminescent sea cucumber does more for the cause than an activist's talking head, and Mortimer seems to understand this intuitively. Whether it's enough is a different question. How Deep Is Your Love sits closest to the lighter end of the BBC natural history tradition, somewhere between a Blue Planet featurette and an art-house nature film — more curious than urgent, more playful than polemical. It is, as the review notes, niche-feeling, and that's not a criticism. Not every documentary needs to be Seaspiracy. Some of them should just take you somewhere you've never been and let you sit with what you find there.
