The Shallows knows exactly what it is, and that's the best praise I can give it. It's barely 90 minutes long, has a small cast, and only one location. Its only purpose is to give you a thrill-ride during that time; an adrenaline rush based on an ubiquitous fear among humans: being stranded in the ocean with a shark. However as the title suggests, this doesn't take place in the middle of the ocean. This woman is stranded only a couple hundred yards from the shore, close enough to potentially shout for help. What The Shallows does so well is establish this sense of isolation and hopelessness for our main character, and her situation of being so close yet so far from safety.
Blake Lively is great in this role. It's mostly a reactionary role - not much dialogue aside from some early establishing conversations to develop her character. For the majority of the film Lively is terrified and fighting for survival against a deadly shark. This thing is huge, like the Jaws' shark's father huge. And it's interesting to see how she follows its patterns and observes its behavior, allowing her to act accordingly without being trapped. There are some far-fetched scenes, sure, but Jaws had them as well and it's hailed as a classic. Now I'm not saying The Shallows is as good a movie as Jaws, because it certainly isn't. But again, the movie knows what it is, and as a short shark thriller appealing solely to our primal fear, it gets the job done and then some.
Now, it has its faults. The electronic music during the surfing scenes was immediately off-putting, and there are some slo-mo shots that definitely did not deserve to be in slo-mo. But the directing as a whole is well done - gorgeous sweeping shots of the open ocean, the slow build up before the initial attack, showing the shark only when it's most effective. The writing is clever and practical, relatable to the point that you feel for this character's predicament, and the acting as I said is top notch. The Shallows doesn't break any new ground, but it does exactly what it sets out to do - give the audience yet another reason to avoid the beach.
