‘How Deep Is Your Love' Review: A Mischievous Documentary Dive Into an Unfamiliar Ecosystem

Yahoo

31-03-2025

Around ninety percent of life forms in the deep sea have yet to be named by humans, British director Eleanor Mortimer informs us in the course of her documentary 'How Deep Is Your Love.' It's a statistic somehow comforting in its vagueness — how, after all, can we put an exact figure on what is unknown to us — and humbling in its vastness, a reminder that we still don't own huge stretches of the globe we profess to run. Across history, any number of explorers, scientists and storytellers have been fascinated by the essential, alien hostility of the ocean to our species, and its enduring status as a place we can only visit but never settle. Mortimer joins those ranks with a film that functions both as awestruck spectacle and anxious warning — joining a literal boatload of marine biologists racing to demystify an ecosystem before deep-sea miners destroy it.
Having premiered at the True/False documentary festival before making its European bow in CPH:DOX, 'How Deep Is Your Love' is a warm, approachable entry in the growing eco-documentary subgenre that should net considerable distributor interest on the strength of its plaintive environmental message and its frequently dazzling imagery — as Mortimer's filmmaking abets the biologists' mission to capture and chronicle an iridescent array of never-before-seen creatures down below. It's not a doc that goes heavy on hard science, instead embracing its layman's perspective, as Mortimer's own running, conversational voiceover whimsically reflects on her own relative smallness and remove from this strange, silent world. The final effect, roughly akin to Jacques Cousteau fused with Mark Cousins, will bemuse some and beguile many.
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A stretch of the Pacific Ocean spanning 1,700,000 square miles and administered by the International Seabed Authority (ISA), the Clarion-Clipperton fracture zone is about as remote a location as one can journey to on Earth — at least a 12-day maritime voyage from the nearest land — but a hotspot for oceanographers thanks to the richness and diversity of life on its seafloor. As they head toward its center, and survey the depths of its 'abyssal zone' (over two miles below the water's surface) via state-of-the-art cameras, the mostly British, millennial-aged team of scientists on the vessel joined by Mortimer doesn't feign know-it-all composure in the face of such familiarity: Their wonder is palpable and easily shared as various exotic, amorphous, luridly painted organisms float into view, identified with decidedly non-academic names like 'Psychedelic Elvis Worm' and 'Headless Chicken Monster.' (Officially naming a species, Mortimer learns, can take up to 14 years.)
There's something endearing about seeing the scientific world this far out of its depth, in all senses of the term, and Mortimer's interview style disarmingly makes the most of this rare leveling of the scales. 'If you had a chance to meet this arthropod, what would you ask him?' she asks one team member about the small, spindly whatchamacallit under scrutiny, cuing an oddball reverie about taking an underwater invertebrate out on a date. There's room for fantasy in a realm where facts are scarce. But there's work to be done too, much of it bittersweet, and soundtracked to the duly plangent strains of Portishead's 'Glory Box.' These extraordinary species must be captured to be studied — using, in amusingly stark contrast to the technological wizardry of the observational equipment, a mechanical device not unlike an arcade claw grabber — and of course die once brought to the surface.
'I feel a bit like the Nicole Kidman character in 'Paddington,'' grimaces one scientist about the essentially destructive nature of his study — and depending on your perspective, this sense of guilt is either amplified or mitigated by the larger-scale threat posed to the seabed by mining companies intent on extracting the precious mineral resources of the deep. Such industrial excavations risk wiping out untold (and, indeed, as yet unseen) natural wonders, though delegates of the ISA are unable to reach an agreement as to how to curb or monitor them.
Back on land, at the organisation's headquarters in Kingston, Jamaica, Mortimer's camera hovers outside stalemate meetings to which she's refused access: the sense of time drifting when there's none to waste is hard to avoid. In a climactic flourish of make-believe, the glowing creatures found on the expedition are airily superimposed on the drab offices and corridors of the ISA building — the film's final, playful but gently pointed reminder that we all share the same planet.
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