For anyone saying to themselves, “Gosh, I wish there were more shark movies” comes 47 Meters Down: Uncaged, the sequel to an unusually chilling film about tourists getting stuck in a shark cage at the bottom of the ocean, gradually running out of air and gradually getting eaten by pissed off sharks.

The original 47 Meters Down was simplistic and contrived, but thanks to some eery direction from Johannes Roberts (The Strangers: Prey at Night) and an earnest lead performance by Mandy Moore, it came across like a creepy theme park ride. Every part of the movie leading up to the shark attack screamed “Don’t go in there!” but in there we all went anyway, to be shocked by sharks, to get lost in the infinite void of the ocean depths, and to have the rug pulled out from under us by a vicious, playful, action-packed finale.

Roberts comes back for the sequel, but aside from a blink-and-you’ll-miss-it shout-out to the previous film’s co-star Matthew Modine, 47 Meters Down: Uncaged stands alone. The characters and the setting and even the sharks are new. Only the contrivances remain. And the premise was already pretty thin. But although Uncaged sometimes struggles to find new ways to thrill us, shark-style, there are just enough scares to make this sequel a decent matinee.

Sophie Nélisse (The Book Thief) and Corinne Fox (Beat Shazam) star as Mia and Sasha, two mismatched stepsisters whose parents, played by Nia Long and John Corbett, have dragged them to Yucatan, Mexico. Their father is doing underwater research, and in order to help the outgoing Sasha get along with her shy new sister Mia, he sends them on a glass-bottom boat trip as a bonding exercise.

No sooner does somebody tell Mia “Don’t get eaten by a shark!” (actual dialogue) are they picked up by Sasha’s friends Alexa (Brianne Tju, Scream: The TV Series) and Nicole (Sistine Rose Stallone), who take them instead to an isolated locale full of underwater caves, filled with ancient Mayan human sacrifice ruins and – wouldn’t you know it? – man-eating sharks.

One thing leads to another and all our teen heroes get trapped in a completely submerged city, a labyrinthine death trap that’s teeming with bizarre underwater creatures. The sharks have lived down there without light for so long that they no longer need eyes to see, so they don’t have eyes anymore, and they just sorta float around the hallways hoping to run into something edible. Which they do. A lot.

The 47 Meters Down films aren’t subtle motion pictures, and there’s no sense complaining that their stories are highly implausible. You either accept that somehow these teenagers with almost no scuba diving experience are going to wind up in an underwater cave system full of ghostly killer sharks or you go see something else, because there’s nothing else here for you. Both 47 Meters Down films are as straightforward as storytelling gets. That’s the selling point, not the critique.

Fortunately, Johannes Roberts has a few clever tricks up his sleeve. The film is packed with left-field set pieces that change the rules of survival at a second’s notice, distinctive lighting choices that turn murky corridors into aquatic haunted house hallways, and at least one winking reference to another silly shark movie classic. The fun of watching 47 Meters Down: Uncaged isn’t so much wondering how our heroes are going to get out of this, it’s wondering how our filmmakers are going to keep them down there and occupied for the length of an entire feature film when there are so few directions you can go with this set-up, and in this space.

That being said, Uncaged still manages to take that goodwill and stretch it ‘til it snaps. The conceit from the original movie, that the divers are able to talk underwater via radios (even though there’s nothing covering their ears that would allow them to do that) is back and it’s sillier than ever. It’s hard to keep track of who’s bickering with who when you can barely see anyone’s faces and nobody’s mouths seem to be moving and they’re too busy swimming to act with their whole bodies. And the gags the filmmakers employ to create “boo” scares underwater are sometimes quite laughable, and in the wrong way. It’s one thing to giggle because you were just scared by a fish, it’s another thing to guffaw because that fish literally screamed at you.

The submerged ruins of 47 Meters Down: Uncaged also create as many problems as they solve. It’s a neat locale for a horror story, and perhaps something could have been done with the Lovecraftian appearance of these sacrificial altars surrounded by spooky statues, but it’s ultimately just window dressing. Almost all the confined spaces our heroes wind up in look interchangeable so it’s hard to tell where anything is in relation to anything else. It should feel claustrophobic. Instead, it’s mostly just vague.

And yet, 47 Meters Down: Uncaged never completely goes belly up. It’s amusing to watch Roberts and his crew struggle against the extreme limitations of their premise, and the film’s cast – especially Nélisse, Corbett and Long – do a decent job of humanizing their cookie-cutter characters, so you don’t want anything terrible to happen to them. Some of the scares will make you jump, and the pale, giant, eyeless sharks are distinctive and scary monsters to put in a “when animals attack” genre flick.

But in the end, 47 Meters Down: Uncaged doesn’t find its own identity. It feels like just another sequel, offering a general approximation of the more novel experience of watching the original. It really is pretty much made for people who genuinely think there aren’t enough shark movies and are eager to see filmmakers try, desperately, to keep the subgenre seaworthy. And to be fair it’s swimming along. It’s just starting to lose its teeth.