47 Metres Down – underwater shark drama with lots of bite but not much depth

In a film where all the dialogue is gold, my favourite line in Withnail and I has to be Withnail’s howl of anguish, on coming to terms with the dreadful implications of a weekend away in Uncle Monty’s country cottage: “We’ve gone on holiday by mistake.” It’s funny, and it expresses a truth about taking holidays in cinema. They are almost always occasions for misery and disruption.

Nowhere is this suspicion of holidaying more strictly enforced than the horror film. This is a genre in which Bad Things happen to anyone foolish enough to take an overseas break. In 2006 an actor playing an unfortunate US backpacker in the torture porn Turistas apologises to the people of Brazil for defaming their country – but really, it’s just an occupational hazard for tourist authorities the world over.

With 47 Metres Down it is the US’s more immediate neighbour that’s owed an apology. Two preppy young American sisters, Lisa and Kate, have travelled south to a fancy resort by the sea and are enticed on a diving excursion with a couple of
 personable locals. “It’s Mexico,” one of their dinner dates says to Lisa’s trepidatious
 response, “it’s totally safe!”

Uh oh. To be fair, Lisa has grounds for her reservation. The proposal is to take the two women miles from the coast, suit them up in scuba gear, lock them in a cage, then lower them into the sea so they can observe the many sharks that infest these waters. And Lisa’s unease only mounts when she catches sight of the cage: a rickety old thing connected via a threadbare wire to a boat that, like its American captain (Matthew Modine, in a dodgy bandana), has seen better days. So, Lisa’s doubts notwithstanding, the two women are duly submerged, and the film proper begins. As an experiment in less-is-more narrative, 47 Metres Down must count as some kind of success.

Most of the film takes place underwater, and most of that in a cage, with two characters whose faces are obscured by cumbersome masks. Relishing these limitations, the director Johannes Roberts and his scriptwriters have nonetheless made a film that exerts a clammy hold.

Something goes wrong – of course it does! – almost immediately: the cable connecting the cage to the winch snaps, and the girls plummet to the ocean floor. From there on, it’s a case of the filmmakers piling on one catastrophe after the other. There is much hyperventilation (to the detriment of diminishing oxygen levels); a temperamental radio link to the surface; and all the while the sharks are circling. In so far as you can judge performance from the expressions behind the masks, Mandy Moore and Claire Holt are decent value as the two sisters. Kate is initially the more intrepid, resourceful one; Lisa is nervy (variations of “Kate, I’m so scared,” is a constant refrain) – mopey from a recent break-up and frankly a bummer as a holiday companion and cage coinhabitant. But as the minutes pass underwater Lisa emerges as much tougher than she first seemed.

As an experiment in less-is-more narrative, 47 Metres Down must count as some kind of success.

However, if you’re after richly delineated character studies I’d be inclined to direct you elsewhere. “How deep do you think it goes?” Kate asks Lisa before their watery descent. Applied to the film, that question is easily answered. Not very deep at all. This is a cheerfully superficial film that orchestrates effective, and sometimes surprisingly nasty, thrills with unpretentious efficiency.

47 Metres Down is in cinemas from July 28