From its poster, “47 Meters Down” looks like one of those Syfy flicks like “Sharknado” or “Lavalantula” which are enjoyable for being infinitely silly and having pathetic CGI effects. Or perhaps it would be like one of those knockoff movies from The Asylum, a production company shameless in capitalizing on blockbuster films by using titles and screenplays similar to them (“Snakes on a Train” or “Transmorphers” anyone?). Perhaps the filmmakers wanted to make something similar to the 2016 sleeper hit “The Shallows” which stared Blake Lively as a surfer who has to use her wits in order to keep from being eaten by a great white shark. Either way, I came into this movie figuring it would be one you should not take the least bit seriously and enjoy for all the wrong reasons.

But to my surprise, “47 Meters Down” is a very effective thriller which is lean in its execution, and its main intent is to take you on a pulse pounding ride. In many ways, it is like Renny Harlin’s “Deep Blue Sea” which, while by no means an artistic triumph, played around with the clichés we remember most from shark movies like “Jaws,” and it employs them to where we think we know what to expect, but our expectations are thrown for a loop. What results is a motion picture which knows exactly what it needs to do and how to do it.

Mandy Moore and Clair Holt star as Lisa and Kate, sisters who, as the movie starts, are on vacation in Mexico. One night they run into some local guys who invite them to go cage diving for sharks. Just like Richard Dreyfuss in “Jaws,” these two women will be lowered into the ocean in a cage where they will get to see those sharp-toothed creatures up close without being eaten. But of course, we all know things will not go as planned as our two leads and the characters around them make one stupid mistake after another. Then again, if they didn’t make those mistakes, there would be no movie.

The clichés abound in “47 Meters Down” as the boat the ladies will be traveling on looks far too rusty to sail anywhere safely. You have Matthew Modine on board as the captain of the ship, Taylor, and I couldn’t help but be reminded of Quint from “Jaws.” There’s also the fact that these ladies have never scuba-dived before, and you know this is just asking to invite disaster. We have the air gauges which act as the plot’s ticking time bomb as the ladies threaten to run out of air sooner than they think, they cut themselves to where blood flows from their bodies, thus inviting any shark in the vicinity to drop by and feast on human flesh, and there’s always the one guy who is there to save everybody’s ass, but we all know how long he will last (or do we?).

Lisa also exhibits tremendous anxiety about doing this even as Kate assures her this will be the best time the two of them have ever had (it won’t). Hearing this conversation between them immediately reminded me of a number of “Star Wars” characters saying this infamous line from one movie to the next: “I’ve got a bad feeling about this.” Another unforgettable piece of dialogue which crossed my mind was Jon Voight’s line from “Deliverance” when he said to Burt Reynolds, “Let’s go back to town and play golf.” This was good advice which was left unheeded, and it makes perfect sense how Lisa’s common sense could be overturned by Kate’s need for adventure.

As you can imagine, everything goes terribly wrong as the boat winch breaks, and the women plummet down 47 meters to the seafloor. Director Johannes Roberts wisely keeps the majority of the action underwater as Lisa and Kate struggle to stay calm and not use up their dwindling supply of air. He puts us right in their shoes as, like them, we are left to wonder what the crew members in the boat are doing to bring them back to the surface or if they are doing anything at all. Roberts is also aided strongly by a pulse-pounding film score from Tomandandy whose work on “Killing Zoe” and “The Hills Have Eyes” remake rank among my favorites. Their music heightens an already intense motion picture to something which will fry your nerves and leave you on the edge of your seat even as we are forced to endure some unintentionally hilarious moments.

Granted, you can’t always expect David Mamet or Aaron Sorkin to be underwater with you when words fail you. When Moore cries out about how the shark almost got me, the audience I was with couldn’t help but laugh as it seems like such a silly thing to say. But then again, what would really say if we were stuck in the same predicament? I doubt we would be uttering a monologue out of Eugene O’Neill’s “A Long Day’s Journey into Night.” Of course, it always helps to have John Milius around when you need him.

Moore and Holt do strong work in creating a bond between and work hard to create characters who, while not having too much in the way of depth, quickly realize they need one another to survive this ordeal. Seeing one of them take off their mask and remove their oxygen tank just to get through the bars of the cage is enough to make one shiver, and this is accomplished without the use of special effects. The actresses are also aided by actor Matthew Modine who plays the Captain of the boat, Taylor. For the most part, we hear his voice more than we see him, but he gives strong support as he encourages his guests, people he never should have put in any danger, a reason to stay calm. In addition, he also reminds the ladies and the audience that the bends is not just the title of a Radiohead album.

Roberts previously directed “The Other Side of the Door,” a supernatural horror thriller which started off well, but later got bogged down in clichés it would have been smarter to avoid. “47 Meters Down,” however, is all about clichés, and just as Harlin did with “Deep Blue Sea,” he manages to manipulate those clichés to where we think we know what to expect, and then we are totally caught off guard. Just watch the scene where the actresses are playing around with an underwater camera, and you will understand what I mean.

Yes, the sharks are CGI, but they are still frightening antagonists in this movie. After a while, the terror comes from a combination of what we think is going on above the water as well as what we cannot see. The water is made to look especially murky to where we can’t see much of what is in front of us, and this leads to an especially scary moment when a character swims out to a certain point, and then suddenly can’t remember the direction in which she came.

Look, “47 Meters Down” is not Oscar material, but it never pretends to be either. While it may not reach the heights of “Jaws” or the unbearable intensity of “Open Water,” it is a taut thriller which will allow the audience a nice diversion for a couple of hours. Roberts and his cast understand exactly what this movie aims to be, and they deliver in a way which will get your adrenaline pumping. You can laugh all you want at the foolishness of the characters, but in this instance their foolishness is necessary for this movie to work at all.

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