“Deep Fear” isn’t a straight-up “Dead Calm” knockoff, despite the similarities in these waylaid-at-sea stories.

It’s still about a sailboat hijacked by a person or persons the skipper stopped to rescue. The nautical props and “weapons” are going to be the same and some of the story elements are over-familiar.

But this Caribbean thriller has sharks and some impressive underwater footage of dealing with those killers while trying to get someone out of a sunken boat. So they’ve got that going for them, if nothing else.

Mãdãlina Ghenea plays Naomi, whom we thought drowned when her family’s sailing yacht sank off the Bahamas in a storm 15 years ago. But here Naomi is, on a high-end 50 foot sailboat, diving off Guadelope with her nephew (Ibrahima Gueye) and beau/business partner (Ed Westwick), sailing past Dominica for her home island of Grenada.

She’s done all right for herself. Insurance settlement?

The trio are separated due to an impending business deal, which is puzzling because why wouldn’t vacationing nephew Barny stay to help sail the boat home? Jackson has a meeting, but Barny?

Anyway, that’s why she’s alone at sea, racing ahead of a coming storm, fielding worried sat phone calls from Jackson but sure of her solo seamanship.

She lets Jackson know when she sees people adrift on wreckage, but doesn’t alert the Coast Guard. The castaways (Macarena Gómez, John Paul Pace) are grateful but frantic. Somebody else is trapped in an air pocket in the trawler that went down.

The fact that they insist Naomi dive down without calling for assistance or alerting the authorities to a sinking should be her “tell.” But never mind.

She and survivor Tomas dive down and fetch Jose (Stany Coppet). Damned if Tomas doesn’t get eaten by a shark on the way back up.

Gloves are off, cards are on the table. There’s something on that sunken boat that a suddenly menacing and all-business Maria and Jose want. Storm be damned, sharks be damned, Naomi is going back down there to get it.

Even hearing “We have no idea how to sail a boat” doesn’t alert Naomi to the leverage she has in this situation. In a panic she gives in. Jackson, who has been tracking her progress, is increasingly alarmed at her radio silence.

The screenplay by Robert Capelli Jr. and Sophia Eptamenitis is mostly dull and almost always predictable. There’s an idiotic bit of Naomi flashing back to the trauma of her near-death at sea decades ago. And yet, here she is, sailing and diving without a care or a hint of PTSD about her, aside from those flashbacks.

But the French cable network Canal+ put money into this, so the digital sharks and underwater calamities in Marcus Adams’ film are slick and convincing. It’s just that Adams had a couple of poorly-received thrillers — “Long Time Dead” and “Octane” — that bombed over 20 years ago, and virtually no credits since.

However exciting the underwater bits are, the film’s lack of urgency kills any sense of suspense. Star Ghenea may be a looker but has little presence and never seems comfortable doing much more than posing on camera and rarely sounds at ease delivering the screenplay’s inane dialogue.

Any movie with a taste of “The Islands” and the gin-clear waters of the Caribbean will always have some allure. But this one just reminds us of all the superior thrillers with similar stories, characters and settings that came before it.

Rating: TV-MA, violence, drug content

Cast: Mãdãlina Ghenea, Ed Westwick, Macarena Gómez, Ibrahima Gueye, John Paul Pace and Stany Coppet

Credits: Directed by Marcus Adams, scripted by Robert Capelli Jr. and Sophia Eptameniti. A Netflix release.

Running time: 1:25