“There’s a comfort to cynicism,” intones Kristen Stewart’s voice-over in the opening scene of the undersea creature feature “Underwater.” “There’s a lot less to lose.” She’s setting up the themes of the picture, but she’s also accidentally preparing her audience for what’s to come: lower your expectations on this one, folks, and maybe you’ll find some satisfaction. We are, after all, talking about a wide January release, and one that’s been sitting on the shelf for so long that T.J. Miller’s in it; principal photography wrapped clear back in May of 2017 (just as “Baywatch” and the Tom Cruise “Mummy” were hitting theaters – were we ever so young?). Handed off to Disney in their Fox acquisition, it was presumably finally released now in order to ride the K-Stew Blockbuster coattails of “Charlie’s Angels.” Good plan!

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Stew and crew are several miles below sea level, on an oil-drilling expedition in the Mariana Trench, information helpfully provided by the opening credit sequence’s web grabs and newspaper screenshots (the source, apparently, was The Daily Exposition). The telegraphing is comical, but credit where due: as a result, director/co-writer William Eubank doesn’t have to waste much time on set-up and throat-clearing. He leaps right in with a slam-bang sequence of water breaching the “command and control” unit of the complex, and the narrative simplicity renders the early passages weirdly effective, its characters dealing with simple, understandable obstacles (falling walls, gushing water, tight spaces, potential electrocution) as directly as possible.

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There’s little time for introductions anyway – that breach leaves the structure in shambles and the survivors’ lives in danger due to an impending “core meltdown,” so they climb into diving suits, moving through access tunnels and across the ocean floor to a safer station a mile or so away. The crew is a real Tournament of Roses Parade of stock characters: the taciturn pro (Stewart), the steady-handed leader (Vincent Cassel), the wisecracker (Miller), the fraidy-cat (Jessica Henwick), the cowboy (John Gallagher Jr.), and the Black guy who dies first (Mamoudou Athie). Apologies for the spoiler, but seriously, we’re still doing that last one in 21st-century horror movies?

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As you’ve probably guessed, “Underwater” is something of an assemblage of spare parts: “Alien” most obviously, though you’ll also hear echoes of “Event Horizon” and your choice of titles from the 1989 undersea horror derby (“Deep Star Six,” “Leviathan,” “Lords of the Deep,” etc.) There are copious pod doors slamming and walls creaking, and lots of opportunities for characters to ask, “What was that?” a question answered by an eerie silence, punctured by bumps, clangs, and screams. Most of the film’s scares, sadly, are of the jump variety – usually caused by the sudden appearance of a creature, accompanied by an appropriately grating screech-sting.

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The main reason to see this one – perhaps the only reason – is to see what Stewart does in the Ripley role (though her close-cropped hair is closer to “Alien 3”). The crew’s mechanical engineer, Stewart’s Norah is such a pacifist that she’s seen, in scene one, gingerly assisting a spider out of a sink, so she doesn’t take the deaths of her fellow crew members well. It’s an all but impossible role, but Stewart is never less than credible or compelling; even her goofiest moments land with gravitas. That said, her very serious, motivational monologue is a misfire; she’s always better at conveying those emotions through action, not reams of dialogue.

And there are other, scattered pleasures – it’s always fun, for example, to watch Cassel slum, particularly as he strains not to straight-up wink at the audience while mouthing early, assuring dialogue like “Listen to me: Everybody’s getting out of here alive, you hear me?” and “Listen to me: you’re not gonna die, ok?”

The rest of the supporting cast doesn’t make much of an impression, or at least much of a positive one; Miller’s frat-boy surliness, to be clear, has not been missed, and his wacky quips land with a series of progressively louder thuds. His character’s death recalls Harry Connick Jr.’s in “Independence Day,” in that I nearly cheered aloud before realizing it wasn’t really intended as a “crowd-pleaser” moment.

The picture’s biggest problem, aside from its general mix-tape nature, is inescapable: it’s just very hard to see much of anything that’s happening, since they’re, y’know, underwater. We get a lot of murky POV photography, and some attempt to use the opaqueness of their surroundings for purposes of suspense – hiding the threat in the darkness and shadows is, for a time, effective. But it’s ultimately mighty difficult to execute anything resembling cogent onscreen action in these circumstances.

You’ve gotta give “Underwater” this much, though: it’s not boring. It’s brief (95 minutes), knows exactly what it is, and Stewart and Cassell seem to be having a good time. If it came out twenty years ago – and, let’s be honest, that’s about when it should’ve – you’d put it on your stack of Friday night video rentals and watch it third, half-asleep and half-drunk at 1 in the morning. And you’d be modestly entertained. [C]