There’s been a lot of talk about Open Water, the frightening new nightmare to end all nightmares, as being "the Blair Witch of the seas." But this shot on video tale of a likable young couple who find themselves accidentally adrift in dangerous Caribbean waters, terrorized by what lies beneath the surface, is an even more streamlined, primal and chilling experience than its docu-shock predecessor. It’s a real cinema chiller that out-scares every horror picture this year by simply knowing, perhaps too well, the primal terror of realizing how absolutely helpless we are in nature’s ferocious hands.

The story is deceptively simple, and since the film runs a mere 77 minutes, writer/director Chris Kentis and company waste no time establishing their sweetly affectionate, slightly strained yuppie marriage between Susan (stunning Blanchard Ryan) and Daniel (Daniel Travis), weighted down with ringing cell phones and 24/7 careers enroute to a much-needed tropical getaway.

After settling in and soaking up some local color, the Type A duo head out to sea on a chartered morning scuba trip that quickly turns disastrous when they’re inadvertently left behind, bobbing on the open water with no rescue in sight. Amusement soon gives way to worry, which soon yields to sickness and fear, to say nothing of the paranoia that unwanted guests and cruel nightfall deliver.

The film is a spiraling nightmare that holds you in a vice grip. The lovers face all manner of real-life horrors, from sickness to jellyfish stings to nibbling fish, before graduating to serve as prey for hungry sharks that just won’t seem to go away, despite Daniel’s "Shark Week" tidbits about how not to become targets.

The film, shot on video, looks it throughout, and that’s not necessarily a bad thing. It lends the film an intimacy that, though awkward and a bit soft in its opening scenes, packs a wallop as the film progresses and you realize just how much danger Ryan, Travis, Kentis and the crew of four experienced up-close, without the safe distance of shark cages or protection.

Despite the low-budget medium, Kentis shrewdly selects his shots, edits and paces the whole thing in such a cinematic way that you’re engrossed nonetheless. And the actors, particularly Ryan, are likable and refreshing. They’re funny, sexy and cool. Once they hit the high seas and submerge into the open water, and find themselves floating in the abyss, it’s a testament to Ryan and Travis how much we like them and want to see them get out alive. Kentis has other ideas in mind.