It takes a very special talent to talk to oneself onscreen and not look stilted or self-conscious. Skilled Shakespeareans pull it off in their soliloquies. Tom Hanks got an Oscar nomination for sharing most of his scenes in Cast Away with a volleyball. Blake Lively is a perfectly decent actor, but she's not quite in that league. So when her solitary survivor in The Shallows laments her situation or pep-talks herself, one may wish the filmmakers had chosen instead to keep her quiet, like Robert Redford's nameless sailor in All Is Lost.

The two films share a basic (and always compelling) premise: one small human being versus the deep blue sea. The Shallows is a survival horror drama from director Jaume Collet-Serra (Non-Stop) that finds Lively's character, a surfer named Nancy, stranded on a rock in the ocean off Mexico. The beach is a mere 200 yards away, but a great white shark patrols those shallows. Nancy already made the mistake of crossing his feeding ground and barely escaped with a deep gash in her thigh. Considering the predator's propensity for chomping on everyone who's ventured into the water since then, it's a safe bet he's hungry, pissed or both.

The computer-generated shark isn't a speaking player, so his motivation remains unexplored. Nancy, by contrast, gets an elaborate backstory about a family tragedy and a need to reaffirm her commitment to medical school. Screenwriter Anthony Jaswinski seems to think it's imperative that his protagonist have a relatable dramatic arc — not realizing that all these soap-opera-ish tropes actually detract from the primal appeal of survival dramas. We don't want Nancy to find a way off that rock (as the clock ticks down to a tide that will submerge it) so she can resolve her issues. We just want her to outwit the shark so we can believe we would, too.

Collet-Serra gives the film sufficient visual interest to sustain our investment in that minimalist scenario for 86 minutes. Aerial shots allow us to map the entire area, and the shark pops up in enough startling underwater images to excuse the absurdity of its behavior. (It might as well be Michael Myers of the Halloween franchise, with fins.)

Sometimes, though, the filmmaker pretties things up too much, giving the scenes of Nancy surfing a music-video sheen as the camera lingers on Lively's bikini body. For those of us who prefer our survival dramas bare-bones and gritty, like Open Water, The Shallows may come across as the CW version. Its photogenic slickness detracts from its terror.

Similarly, Nancy's prattling running commentary actually makes her less sympathetic than a stoic silence would. Happily, in a stroke of brilliance, the filmmakers have given her a scene partner of sorts — a seagull with a wounded wing. The avian actor's name is Sully, and, in an interview with Vulture, Collet-Serra called him "kind of like the Marlon Brando of seagulls."

Snicker all you want — it's only half hyperbole. Sully's naturalistic reaction shots single-handedly rescue several scenes in The Shallows that would otherwise feel interminable. Some audience members may end up caring considerably more about the plucky gull's fate than about Nancy's future as a doctor.

Our heroine was foolish enough, in classic slasher-flick fashion, to think she could enjoy the isolated, pristine beach and then simply Uber herself out of there. The bird's indignant squawks and skeptical head tilts remind her that plans can go sideways in an instant. In a cinematic world dominated by fanciful CG critters, and in a film too glossy to evoke our abject dread of the deep in any consistent way, Sully deserves some kind of award for keeping it real.