Man, could this movie have used a sharktopus. And, no, that's not a sentence I ever expected to write, but that's how bad Sanctum is, it makes me wish it were an even worse movie so at least something, anything, remotely interesting would be happening onscreen.

Sanctum is a movie about cave divers. That is, guys that go down into deep dark holes finding new tunnels and underground waterways in hopes of seeing things that no one else has ever seen and getting in National Geographic. They are a tough group of pioneering folk who can handle rough conditions and get through a tight squeeze. For this particular group of cavers, who are at least partially based on real people (including co-writer Andrew Wight), this is the expedition where the conditions get too rough and the squeezes too tight. A cyclone hits while the team is miles below the surface, and the flooding forces them to improvise new escape routes.

That's really the long and short of it. I went in with really low expectations for this one, and somehow the movie still managed to do the limbo right under them. Once upon a time Sanctum would have been a forgettable B-picture, stuck on the bottom of a bill with a better movie in an attempt to fill out the program and still give people their money's worth; on its own, it is a rip-off. From start to finish, it is one predictable scene after another, full of obvious twists and turns and, honestly, no surprises whatsoever. If you ever wondered how long it would take to run through every cliché movie line from the last century-plus of cinema, Sanctum will tell you: it's 109 minutes. Though, to be fair, when the acting is as wooden as it is here, it feels more like 999. If this were a SyFy movie, the guys at "The Soup" would be combing it for the best worst clip right now.

I wasn't really looking to get that much out of Sanctum. The main selling point, as touted in the trailers and TV commercials, is that it was produced by James Cameron and "conceived and shot in 3D." The prospect of Cameron's Avatar-tested technology applied to rocky peril far below the Earth was enough to sign me up. Who doesn't want some cool spelunking adventure, full of stones falling out of the screen right at you? Thrills in three dimensions!

Yeah, you'd have thought. Turns out, no one remembered where they packed those thrills when they were getting ready to travel to the shooting location, and so the crew had to carry on without them. Australian director Alister Grierson is a competent director, but he's not very imaginative. Judging from Sanctum, he's the kind of guy you hire to get the job done, and he'll deliver it on time and on budget, but he's got nothing to impress you with beyond that. Okay, to be fair, for about half an hour, the 3D photography was pretty remarkable. Right up until the beginning of the storm, when we see the rain falling into the gaping pit from a vantage point somewhere up in the sky, the whole thing looks really neat. That's also when the action is getting started, so you'd think it's when the whole picture is going to go gonzo. Think again. From that scene onward, the impact of the 3D steadily softens, and it gets to a point where you won't even notice it anymore. I lifted my glasses two or three times just to make sure I still needed them.

Which isn't good. That's what I expect from Clash of the Titans, not from a movie that was put together to give James Cameron another excuse to show off his expensive toys. It's a high-definition travelogue built around a low-definition script. If you really have a yen to see some caves on film, go to the nearest IMAX and see what they have on schedule for their nature documentaries. Or get The Descent on Blu-Ray and let a creepy monster kill the cave divers rather than killing your time watching Sanctum.

Jamie S. Rich is a novelist and comic book writer. He is best known for his collaborations with Joelle Jones, including the hardboiled crime comic book You Have Killed Me, the challenging romance 12 Reasons Why I Love Her, and the 2007 prose novel Have You Seen the Horizon Lately?, for which Jones did the cover. All three were published by Oni Press. His most recent projects include the futuristic romance A Boy and a Girl with Natalie Nourigat; Archer Coe and the Thousand Natural Shocks, a loopy crime tale drawn by Dan Christensen; and the horror miniseries Madame Frankenstein, a collaboration with Megan Levens. Follow Rich's blog at Confessions123.com.