A young boy plays with his football along a lonely Mexican beach when he notices a dark object washed up on the shore: it is a helmet with a little camera attached, and on watching the footage it contains he is horrified to witness a couple of surfers suffering a shark attack. Some time previously, Nancy Adams (Blake Lively) was an American tourist who travelled to that same beach, alone thanks to her companion trying to get rid of a hangover, but as she was driven to the area by helpful local Carlos (Óscar Jaenada) she came to terms with the idea of being out there solo to surf, for her late mother had introduced her to the sport and she felt she could pay better tribute to her this way...
The dangers of the deep blue sea had been a staple of horrors and thrillers since before Steven Spielberg's Jaws, but come the turn of the millennium there happened along a low budget hit by the name of Open Water which revitalised the subgenre by taking its cue from the Spencer Tracy movie The Old Man and the Sea, which featured the venerable star in an Ernest Hemingway adaptation back in the fifties, pretty much a one man show to boot. Something like this was a gift to the star, since all the focus would be on them and the drama lived or died by their performance, so it was a lot of pressure but if you were judged up to the challenge then the rewards were amply worth the entire endeavour.
Lively was the star in question this time around, following in the recent footsteps (if you can have footsteps at sea) of Robert Redford whose All is Lost detailed a similar ocean-based disaster mainly for one person, though she was assisted every so often by the presence of another supporting performer. Make no mistake, however, she was carrying this film for most of it, inspired she said by her husband Ryan Reynolds' work in the underground thriller Buried, and it would seem she was more than up to the task as she held the focus for as long as it took for Nancy to get her act together. And do what? It was simple: a shark really, really wanted to eat her, and after getting a taste of a thigh it wanted more.
Now, sharks don't think like that, indeed there are some doubts as to whether they think at all as we know the term, as it is more or less instinct that powers their need to keep eating and keep moving, but for the intents here the big fish bore a grudge towards Nancy, sort of a "stay out of the shark's domain" deal. It had been initially drawn to the dead whale that is floating in the bay, but as the woman ventured out to take a closer look, she ends up sitting on said creature trying to fend off the shark, which by and by left her stranded on a rock as it circled, with only an injured seagull for company (named Steven by her, Steven Seagull, geddit?). You had to take quite a bit of this with a large pinch of salt, as it did not stand up to scrutiny if you knew anything about the science of the tides, never mind the science of aquatic predators.
But who cared about boring old science when there's a horror flick to be watched? The screenplay by Anthony Jaswinski had been much-acclaimed before it was made into this movie by Jaume Collet-Serra, a music video director turned feature film director as was the case with many of his peers, which could equally lead the expectations towards the stylish as they could towards the alarm bells, but he did a neat job of sustaining the ebbs and flows of the tension. It was an uncaring world they depicted here, at least as far as Mother Nature went, where it could take away a parent to terminal disease then land her daughter in a nightmare she has a slim chance of escaping, and not everyone who wanders along will be as helpful, though she still holds out the hope that some kind soul will respond to her pleas. There was a certain (sharklike) purity of purpose to The Shallows that made it compelling even as you were questioning the logic of what you were watching, but this was overwhelmingly a star showcase with clever CGI for the heavy lifting of the thrill sequences, and not bad as far as that went. Music by Marco Beltrami.