"A B movie in the best sense, Sanctum — executive produced by James Cameron — is a lean, clear-headed 3-D thriller that knows exactly where it's headed from the moment its adrenaline junkie explorers dive into the world's biggest cave in Papua New Guinea."
— Owen Gleiberman, Entertainment Weekly
"...a subterranean survival epic that expertly tightens the screws even as one wishes it would keep a tighter mouth-clamp on its increasingly whiny characters."
— Justin Chang, Variety
"Here and there an image of spectral beauty, assisted by the 3-D technology, floats into view and captures our imagination. But the script, which really should've been called Sanctimonium, has a serious case of the bends."
— Brian Lowry, Variety
"You can't just play mad libs with the terms 'James Cameron,' 'underwater,' and '3-D,' and expect automatic Titanic. There kinda has to be a good story and passable acting involved, and this is where Sanctum... sucks it."
— Luke Y. Thompson, E! Online
"Instead of exploring the claustrophobic impossibilities of struggling blindly through an endless world of darkness and water, he lets the lousy mechanical screenplay by John Gavin ruin things. There's so much potential here that when the script settles in for its 'dilemma, then death' plot pattern, we grow angry, then irritated, then bored."
— Bill Gibron, filmcritic.com
"...I'm not sure that the movie's second-rate drama, or its shards of manly philosophy, come anywhere close to justifying the arduous and frequently graphic violence of the journey. Will any of these people ever see daylight again? And is it worth leaving your couch to find out? It would be dishonorable to answer those questions, and anyway the second one is entirely subjective. How comfy is your couch?"
— Andrew O'Hehir, Salon