Herman Melville wasn't much of a horror aficionado. But he did understand the sea and its inhabitants pretty well.
Consider the subtleness of the sea; how its most dreaded creatures glide under water, unapparent for the most part, and treacherously hidden beneath the loveliest tints of azure. Consider also the devilish brilliance and beauty of many of its most remorseless tribes, as the dainty embellished shape of many species of sharks. Consider, once more, the universal cannibalism of the sea; all whose creatures prey upon each other, carrying on eternal war since the world began. [Herman Melville]
The author of Moby Dick gets it: There's something scary about the sea and the great big benthos of murky unknown things lurking in the dark. In the depths, where sunlight can't penetrate, seafaring creatures look like tendril'd monsters conjured up in the imagination of H.R. Giger. The sea and its enigmatic inhabitants are prime horror movie material (why has no one made a movie about a Vampire Squid from Hell yet?), yet movies rarely manage to do anything interesting with all that nightmare fodder.
The Shallows, which stars Blake Lively as an attractive woman being terrorized by a shark, doesn't do much to shift the paradigm of bad sea monster movies. It's closer to Deep Blue Sea than Jaws, but without the joy of hearing L.L. Cool J paraphrasing Teddy Roosevelt. Opening a can of tuna with an electric can opener is more frightening, and more rewarding (tuna is high in protein), than The Shallows. And sadly, this is still one of the better shark movies of the decade.
Helmed by Jaume Collet-Serra, who directed the Paris Hilton-starring House of Wax remake, The Shallows does have a few unusual attributes that make it stand out from other awful shark movies. Lively's surfer is stranded on a rock (also, briefly, the flotsam corpse of a dead whale) just 200 meters off shore. She's a med student and wears earrings, both of which come in handy when she gets mangled by the tenacious shark, and she gets really good cell service on a supposedly secret beach in Mexico, which is maybe her most impressive achievement. There's also a cute comedic relief seagull. Aw.
To pad out the slender 87-minute runtime, Collet-Serra gives us a plethora of vivid, slow-mo shots of Lively's surfer carving up glassy waves while four-on-the-(ocean)floor beats blast. Shots of gleaming water usually look very pretty, so he takes a lot of them. It's like he saw a latter-day Terrence Malick movie and thought, Psht, anyone can do that. To remind us that Lively is very attractive, the sun's halation licks her tan, tone body; to make us care about her, we get snippets of her emotional backstory via off-brand FaceTime conversations with her sister and father speaking exclusively in emotional exposition. (It passes the Bechdel Test, so that's cool.)
Roger Corman could have done this better as Girl vs Shark for a fraction of the cost. Indeed, The Shallows is not far removed from the Asylum's flotilla of stupid shark movies (Sharknado 3: Oh Hell No!), which are sometimes aware of their own ineptitude, or at least make for decent drinking games. The CG-shark in The Shallows looks as bad as the hologram in Back to the Future Part II, yet the movie falls short of the so-bad-it's-good status of Jaws: The Revenge, which reaches a sort of idiotic fever dream euphoria by the end. The Shallows is just normal-bad, not campy (a word that, akin to Kafkaesque, has lost meaning by now), and deadened by its PG-13 rating — the violence has no visceral impact (which hurts when the movie is literally just about a shark eating people).
Jaws is, of course, still the best movie about a sea-dwelling monster. As is now common cinephile knowledge, the shark, lovingly nicknamed Bruce, didn't work very well, so Spielberg opted to show it sparingly. In Jaws' wake, movies about killer sharks/whales/piranhas/octopi flooded theaters. They even had the decency to tell you exactly what you were in for: Orca: The Killer Whale. Great White. Piranha. Piranha 2: The Spawning. Mako: The Jaws of Death. Tintorera. Tiger Shark. Tentacles. Italian master of schlock-and-gore Fulci managed to work a shark-vs-zombie fight into Zombi, which makes no sense, but is undeniably awesome. None of these movies are scary, or clever, and none has the audacity of Mike Nichols' The Day of the Dolphin (1973), whose tagline reads, "Unwittingly, he trained a dolphin to kill the president of the United States."
The last decade has been rife with bad shark movies with funny titles: Mega Shark vs Mecha Shark. Mega Shark vs Giant Octopus. Sharktopus. Shark Night 3D. Jurassic Shark. Super Shark. The low-budget Open Water (2004) earned considerable praise for being not-terrible, but it's basically just a pair of people floating in the water for 90 minutes. It's hard to make that aesthetically engaging. Sharknado was a sensation on Twitter, and spawned some sequels, but the last genuinely scary shark movie came out 40 years ago, which is sad. Sharks deserve better.