From executive producer James Cameron (Avatar) comes a thrilling underwater adventure based on true events. Master cave diver Frank McGuire and his team have been exploring the least accessible, uncharted and dangerous underwater labyrinth on Earth. When a tropical storm cuts off their only escape route, they must find an exit to make it out alive. In Earth's inner sanctum, make just one mistake and no one will know you were ever there.

Special Features:

• Deleted Scenes
• Feature Commentary
• Sanctum: The Real Story
• Nullarbor Dreaming