In 47 Meters Down, sisters Lisa (Mandy Moore) and Kate (Claire Holt) vacation in Mexico to help Lisa get over her breakup with a boyfriend who says she’s boring. And he’s right: Lisa is duller than Jersey coastal water. But thrill-seeker Kate is determined to fix that. She drags big sis dancing, and they meet a couple of local hunks (Santiago Segura and Yani Gellman) who tell them they know a skipper (Matthew Modine) who—for a hundred bucks each—will take them on an exciting shark-diving excursion. Kate, of course, is gung ho, but Lisa is wary. “You’re going to have the time of your life, I promise,” Kate tells her. And the girl ain’t lying. Shortly after the two enter a rusty cage (big mistake) and are lowered into the water several miles off the Mexican shore, a mechanical malfunction causes the cage to rip loose from the boat’s rickety crane and plummet 47 meters, or more than 150 feet, to the ocean floor. Panic sets in as the novice scuba divers realize that their oxygen supplies are quickly running out, and if they try to swim to the surface they risk getting the bends or ending up as a snack for one of several great white sharks encircling them. What to do?

Unfortunately, director Johannes Roberts (The Other Side of the Door) and co-screenwriter Ernest Riera do what’s predictable. Even before the gals don their diving suits or get their feet wet, any savvy moviegoer will know exactly who is going to survive this deadly ordeal and who isn’t, because all of the characters—which also include a bullying boat worker (Chris J. Johnson)—are right out of central casting. And it doesn’t help that we stay with Lisa and Kate once they sink into the murky abyss. Everything from that point on is seen from their point-of-view, and while this initially increases the sense of claustrophobia and adds to the tension, the gimmick grows tiresome after a half hour or so. A viewer can only take so much of Moore screaming that she’s going to die; eventually, we need a break. Going back to the surface would also have given the filmmakers a chance to flesh out the captain and his one-man crew, who are now in serious trouble since they illegally threw chum into the water to attract the sharks, to say nothing of their ill-equipped, creaky vessel. It’s a foregone conclusion that the sisters will sue them if they survive, so maybe the skipper and his second-rate Gilligan would consider leaving the girls to die? It certainly would have added to the intrigue, but no such luck.

Moore and Holt deserve credit for making this latest bit of shark-bait cinema as effective as it is. They give it their all, but they’re stuck wearing scuba masks for the great majority of the movie, so most of their acting is limited to voice work. As for Modine, his appearance is little more than a cameo, and Segura and Gellman barely register. A late twist in the story is undeniably effective, but it also feels like cheating, and is insufficient to save this shallow, waterlogged adventure.