‘The Devil’s Mouth’ Review: Cave Swimmers Become Chum in a Shark Thriller With Extra Claustrophobia

“Under Paris,” “Deep Water,” “Thrash,” “Chum” — the shark movies come so thick and fast these days, there’s scarcely any time between them to deem it safe to go back in the water. That said, if this recent run of films is to be believed, regular old beaches are fine these days. Seems the toothy predators are increasingly seeking less obvious locations to graze on wet human flesh: a mid-Pacific plane-crash site, the City of Lights, and now, in “The Devil’s Mouth,” a dark, dank, tight-squeeze cave in idyllic coastal Thailand. This claustrophobic danger zone brings a smidge of novelty to director Jeff Wadlow‘s aquatic thriller, but the formula is otherwise familiar: five hot young things on vacation, one bull shark very much in business mode, and a pecking order that most viewers can guess five minutes in.

It’s odd that the shark movie has lately joined the romantic comedy in the ranks of genres most favored for straight-to-streaming fodder, since its pleasures, from “Jaws” onwards, have traditionally been communal, cinematic ones: From the safety of your sofa, a great white jump scare just doesn’t land in quite the same way. A Prime Video release, “The Devil’s Mouth” sometimes feels ill-suited to the small screen, given the frequently squint-inducing murkiness of its setting; on the other hand, the very lax progression of Aja Gabel and Myung Joh Wesner’s Black List-featured script feels tailored to the requirements of second-screen viewing, with character tensions brewing slowly and repetitively between sporadic feeding frenzies.

If the dialogue and characterization never rise above the pedestrian, however, those tensions do at least bring some malicious rooting interest to the essential survival drama — with a strain of toxic friction evident from the get-go between nice-girl protagonist Sarah (Kathryn Newton) and her narcissistic BFF Max (Lana Condor), a self-declared “CEO of fun,” on their luxury post-graduation vacation. Both stars are better than their thin roles require them to be, with Condor clearly enjoying an opportunity to spike her wholesome “To All the Boys” star persona a bit; perhaps her young fans will resist how blatantly the film’s sympathies are stacked in Sarah’s favor.

Or perhaps not: Sarah has a pretty rough time of it from the start. The unpaired fifth wheel on what is otherwise a lovey-dovey couples’ trip — with Max and mutual college friend Adrienne (Tommi Rose) accompanied by their respective, equally bland boyfriends James (Nico Hiraga) and Greg (Gavin Casalegno) — Sarah is quite literally an afterthought when, at the end of a day’s yacht hire in a picturesque cove, the other four set sail while she’s still in the water, leaving her at the mercy of a smack of jellyfish. Cue an initial sea-creature attack less bloody than those to come, but perhaps the film’s most eerily and alarmingly constructed setpiece.

A cursory apology from Max (“I’m trying to be accountable here,” she says, unconvincingly) doesn’t quite smooth the waters between the two by the time of the group’s next adventure: a remote coastal cave-swimming expedition led by local guide Wat (“The White Lotus” star Tayme Thapthimthong). A cautionary-tale tone soon sets in as the entitled Americans, led by Max, repeatedly overrule Wat’s native expertise. (The safer cave route he recommends is marked on the map in green; the one they choose is marked in red. How many more flags do you need?) You can hardly blame him for leaving them to their fate when, several caves in, ravaged remains float to the surface, followed in short order by the dreaded fin slicing through the water.

How did the beast find its way into these cramped quarters? “I don’t think this is something we need to figure out right now,” says one of the guys, and fair enough, even if that rather lets the screenwriters off the hook. A more immediate priority is navigating a route out of this cave network, with the shark, given limited room to roam, tailing them at every turn. Needless to say, not everyone’s going to make it out alive. The panic-inducing narrowness of the potential escape routes make a change from the genre’s usual spatial dynamics, with Wadlow — recycling some of the atmospherics from his 2020 “Fantasy Island” film, minus the fantasy — and DP James Kniest exploiting those most effectively in a couple of extended, suitably suffocating underwater setpieces.

It’s the shark’s appearances, surprisingly, that lack bite. Denied a point of view or much in the way of a closeup, the CG killer never feels a particularly distinctive or palpable presence, while its lunges take on a fairly predictable pattern. The gore, meanwhile, is unexpectedly discreet, which is a strange place for the film to exercise subtlety: A washed-up sea turtle with a cartoon-style bite taken out of it is the most visceral sight here, and the most saddening. The human bait, on the other hand? Have your fill, buddy.