Sanctum is a 2011 3D action-thriller film[3][4][5] directed by Alister Grierson and written by John Garvin and Andrew Wight.

It stars Richard Roxburgh, Rhys Wakefield, Alice Parkinson, Dan Wyllie, and Ioan Gruffudd.

The film was released in the United States on 4 February 2011 by Universal Pictures to generally negative reviews from critics.

Josh's father, Frank (Richard Roxburgh), a master diver, has already established a forward base camp at a lower level inside the cave, where the team has been exploring for weeks.

As Josh voices his disdain for his father and his opinions about cave exploration, the team below prepares to dive into an unexplored area of the system.

While exploring the entrance to the new system, Judes (Allison Cratchley) experiences a problem with her air tank hose.

In a struggle to determine who truly was responsible for her death, it is revealed by Frank that Judes had dived in an exhausted state since they previously had to retrieve the extra bailout tanks, a task Josh did not do.

and Liz make their way up through "the elevator" (an area leading up to the main entrance of the cave), Josh is unable to leave his father and the dive team behind to their doom and turns back, accompanied by Luko.

Luko is severely injured when the boulder breaks loose, sealing the shaft and throwing him back down into the cavern.

George realises that he cannot continue and after sharing a few words with Josh relieves himself of his pack and hides himself so as not to burden the rest of the team.

The tunnel leads them to a sunlit cavern where an unidentified WWII Japanese tank collapsed through the surface years ago.

[9] Stunt diver Agnes Milowka, who appears as a double in the already-released film, drowned in one of these caves on 27 February 2011 when she reportedly ran out of air.

[10] In striking similarities to the movie script, she also left her spare tank behind, to force the way through the tight restriction, and it is actually her playing Judes' drowning scene.

[11] Universal Studios and Relativity Media paid $12 million for rights to distribute the film in the United States and Canada, and in several foreign countries.

[19] The UK's Daily Express gave it 3 out of 5, writing: "The action doesn't quite conjure up the claustrophobic intensity you expect but the father-son-storyline is sufficiently muscular".