Sanctum

“Executive Producer: James Cameron”—that should tell you plenty right there. You can count on Sanctum to encompass outsized adventure, a monumental filmmaking challenge, thrill-ride dynamics, and the most underbaked script that one of the budget’s more modest line items can buy. You can also wager on it to make a gajillion dollars, and pretty much earn it.

Rather than a distant planet or the ocean’s bottom, Sanctum centers on a crew of elite extreme cave divers led by adventuring hardman Frank (Richard Roxburgh), funded by callow mogul Carl (Ioan Gruffudd), and accompanied by Frank’s teenage son Josh (Rhys Wakefield), who are attempting to plumb the unknown reaches of an utterly remote and unspeakably vast cave system. There’s a big storm coming, but no one’s worried: “Topside’ll give us plenty of warning.” Right. ’Cause people make big-budget epics about everything going fine for 109 minutes. Not even the speed with which director Alister Grierson has to set up the premise and get to the action can explain away the saucer-shallow characters and egregiously clichéd dialogue. (Seriously, notebook page after notebook page filled up with the likes of “He’s a good kid, Frank—cut him some slack,” “Life’s not a dress rehearsal,” and “Carl likes to play by his own rules.”) But once disaster finally strikes, Sanctum kicks into anxious adrenaline mode and stays there.

Perhaps unsurprisingly, Sanctum is presented in 3D. Perhaps surprisingly, 3D isn’t just a pointless gimmick here. There is some extraneous jutting on occasion, but one thing the technology is actually good for, it turns out, is enhancing the claustrophobic nature of squeezing through tight, dark spaces untold miles underground—and underwater, breathing through bulky and complex equipment, mere seconds from drowning or a debilitating case of the bends. Oh, and there are also precarious rock-climbing maneuvers to be managed between dives. In addition to the copious opportunities for instant death or fate-sealing critical injury, the survivors’ few small headlamps are starting to wink out one by one in the cave’s endless dark, and there’s plenty of interpersonal drama to keep things even more tense. And since up isn’t an option, the only way out is down.

Said interpersonal drama follows thrsough on the lack of promise shown at the outset—tough guys are tough to have as dads, rich guys are dicks, chicks just can’t keep it together—but the movie barely pauses for such folderol before delivering you up, quivering, for the next ridiculous nail-biting set piece. Sanctum is so grindingly tense in spots that it barely qualifies as fun, but at least it’s unlikely to inspire an obnoxious vogue for cave diving.

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