I don't think that you would ever catch me caving, at least not beyond having a peek into one you happen upon on a walk. Not least because being cold and wet isn't my idea of fun, couple that to squeezing through tight underwater spaces and you may have discovered one of the thing I would least like to do in life. Having said all that, I quite enjoyed Sanctum.
Overall I think the film is well paced, nicely lit and well directed, as well as managing not to have lots of silly pointless moments that these “escape” movies often have (Daylight, 1996; Alien Resurrection, 1997; Deep Blue Sea, 1999).
Apart from Richard Roxburgh and Ioan Gruffudd, the cast are unknown to me. All are fine, but it is Roxburgh that really owns the film; as the grouchy, belligerent leader of the caving trip he’s perfect, and certainly his arc is the main focus of the film.
Directed by the unknown (to me) Alister Grierson and executively produced by James Cameron, Sanctum is and does nothing fancy, but is never-the-less fun and entertaining. But, you know, that's just, like, my opinion man.