The 3-D action-thriller Sanctum, form executive producer James Cameron, follows a team of  underwater cave divers on a treacherous expedition to the largest, most beautiful and least  accessible cave system on Earth. When a tropical storm forces them deep into the caverns, they must fight raging water, deadly terrain and creeping panic as they search for unknown escape route to the sea. Master diver Frank McGuire (Richard Roxburgh) has explored the South Pacific's Esa-ala Caves for months. But when his exit is cut off i a flash flood, Frank's team-including 17-years-old son Josh (Rhys Wakefield) and financier Carl Hurley (loan Gruffudd) - are force to radically alter plans. With dwindling supplies, the crew must navigate an question: Can they survive, or will they be trapped forever? Shot on location off the Gold Coast in Queensland, Australia, and Sanctum employs 3-D photography techniques Cameron developed to lens Avatar. Designed to operate in extreme environment, the technology used to shoot the action-thriller will bring audiences on a breathless journey across plunging cliffs and into the furthest reaches of our subterranean world.  

Title: Sanctum
Genre: Action/Thriller
Directed by: Alister Grierson
Written by:Andrew Wight, John Garvin
Starring:
Richard Roxburgh, Rhys Wakefield, Ioan Gruffudd, Alice Parkinson, Dan Wyllie
Movie Releases: February 4, 2011

Plot:
"Sanctum follows a team of underwater cave divers on a treacherous expedition to the largest, most beautiful and least accessible cave system on Earth. When a tropical storm forces them deep into the caverns, they must fight raging water, deadly terrain and creeping panic as they search for an unknown escape route to the sea.
Master diver Frank McGuire (Richard Roxburgh) has explored the South Pacific's Esa-ala Caves for months. But when his exit is cut off in a flash flood, Frank's team–including 17-year-old son Josh (Rhys Wakefield) and financier Carl Hurley (Ioan Gruffudd)–are forced to radically alter plans. With dwindling supplies, the crew must navigate an underwater labyrinth to make it out. Soon, they are confronted with the unavoidable question: Can they survive, or will they be trapped forever?"

James Cameron is probably involved in the movie Sanctum because he's himself found of diving. But judging from the plot, it definitely sounds like Sanctum could be a hell of a thrilling movie.