Sharks must keep moving or they’ll drown. It’s the same trait which The Shallows adopts wholeheartedly. Cutting through such murky waters as plot and character-building, it goes straight for your adrenal gland with vicious precision – and while it may not leave a life-long scar, it certainly does enough to keep you out of the water for a little while.

Our heroine is Nancy Adams (Blake Lively), who has dropped out of medical school and tracked down the secluded Mexican beach to which her recently departed mother first came when pregnant with Nancy.

The film takes no time in poking gentle fun at our mourning all-American sweetheart, as the amiable local who gives her a ride to the place he’ll only call ‘paradise’ urges her to put away her phone and “live in the moment.” It’s a home-run cliche, of course, but you just paid money to sit in a cinema and watch a film about Blake Lively fighting a giant shark; no one’s pairing this with The Neon Demon on a double bill.

A film with its tongue lodged so firmly in its cheek needs a main character who can roll with that, and it turns out that Lively is perfect for the role. Her previous performances in pieces like The Town and The Age of Adaline show that she has, perhaps, rather more depth and range than people are inclined to give her credit for, and she’s so clearly having fun here that it’s hard not to be swept along with the tide.

It also takes no minor acting chops to have the screen almost entirely to yourself for the best part of an hour, with nothing to play off except a great white piece of CGI the size of a tank.

And that’s your film. With 200 metres of pristine ocean between her and her egregiously product-placed phone, Nancy has only her basic medical training and, of course, the deep reserves of emotional strength she draws from the memory of her mother to get her through.

It also involves Blake Lively spending extended periods of time sprawled on a rock in her bikini, which will probably account for a decent chunk of the film’s box office takings, but even that doesn’t seem too lascivious in light of the general good humour and some watch-it-through-your-fingers scenes of amatuer self-surgery. Take note, Suicide Squad: when Blake Lively zipping up a wetsuit in slow motion seems less pervy than Margot Robbie bashing monsters with a baseball bat, you’re really doing something wrong.

With all the rampant cultural nostalgia marching across our screens at the moment, The Shallows serves as a timely reminder of what exactly a good throw-back movie actually looks like. It’s all well and good piling special effects on top of some resurrected ‘80s title, but just as punk punctured all the pomposity of the concept album extravagance that came before it, so too did much of that decade’s most enduring cinematic work; bringing lean, straight-forward action back to a medium which was becoming dangerously focused on its own navel. It reminds us of the sheer fun which those films were, in a way that few movies today (Mad Max: Fury Road being a particularly notable exception) seem to manage.sumo suit

That’s not to say that the film doesn’t have its share of flaws. The whole ‘power of family’ bit gets a little overplayed towards the end, and the gang of surfers seem curiously oblivious to the huge rotting whale carcass floating a hundred feet away from them, until the camera decides to introduce it to us.

But these are minor quibbles; the film deftly hits the beats of tension and action, and with an 86 minute running time it never drags and you still feel like you get enough bang for your buck. As the title suggests, this movie has little interest in going much beyond its fishhook of a premise. But most shark attacks happen in less than six feet of water, and The Shallows is the perfect summer flick to drag you under. 4/5

Check out the rest of the latest cinema releases in our new movie reviews section, including the new wartime thriller Anthropoid.