The driving force behind Sanctum is co-writer Andrew Wight, whose own experiences being trapped under the Nullarbor Plain while caving inspired him and writing partner John Garvin to create an original story about an ill-fated caving expedition in Papua New Guinea. Similar to Wight’s own experiences, the group of characters in Sanctum are put in extreme danger when an unexpected flood prevents them from being able to leave the cave. In the film the characters have to dive and climb their way out of the unexplored tunnel system while fighting dwindling supplies, limited air, hypothermia, decompression sickness and panic attacks.
Wight has previously enjoyed a long partnership as a producer working with filmmaker James Cameron on Cameron’s 3D underwater documentaries Ghosts of the Abyss and Aliens of the Deep. Wight was also involved with Cameron and his engineering partner Vince Pace on the development of the Cameron/Pace Fusion 3D Camera System that was used so expressively on Cameron’s Avatar, the film that still boasts the best use of 3D technology to-date. As with Avatar, the 3D in Sanctum is not a novelty (or worse, a tacked on post-production afterthought) but it exists to immerse the audience into the world of the film. In the case of Sanctum, the unobtrusive 3D does gracefully express both the natural beauty of the unspoiled underground wilderness while also very successfully conveying the claustrophobia, emptiness and isolation in key scenes. The problem is that any moments of wonder, tension or drama are ruined as soon as any of the characters open their mouths.

Despite being full of actors who have demonstrated their talents in other roles (including television and theatre) Sanctum is full of moments that provoke unintentional laughs or stunned disbelief that a film of this scale would allow for such cringe worthy dialogue. Most shocking is Welsh actor Ioan Gruffudd, who was magnificent in Amazing Grace among other things, but is unrecognisably bad in Sanctum playing a cocky American who is the expedition’s financier. In the role of the expedition’s lead diver, Richard Roxburgh seems to have been directed to continuously growl, making Christian Bale in the The Dark Knight sound effeminate by comparison. The rest of the cast do the best that they can with what is written for them but they cannot overcome the clichés and crude lines such as “What could possibly go wrong, diving in caves?” Embarrassing overt Australianisms such as “flooded like a blocked dunny”, “fizz up like a dropped can of beer” and “tighter than a nun’s nasty” don’t help the cause either.
The script is also structurally flawed as the film very quickly establishes a pattern of crisis moments that all but one of the characters makes it through. There is also some very heavy signposting to how several of the characters will be dispensed with making their demise predictable and uneventful. This type of simplicity and obviousness is in itself not a problem, but when compounded with the weak dialogue and poor characterisation it does add the degree in which Sanctum is so difficult to engage with. However, to be fair, not all of the crisis/character demise moments are bad and the film does contain one or two extremely impressive scenes that are both moving and exciting.
The juxtaposition between the impressive visual components of Sanctum and the excruciating dialogue is extraordinarily pronounced. Rarely has one film contained such extremes in quality from its different parts and unfortunately its weaknesses unforgivingly overwhelm its strengths. There are so many great moments in Sanctum but the film continually thwarts any good that it has done with mood-killing hammy dialogue. We can only speculate if an originally simple and straightforward script was tampered with to make the characters more ‘colourful’ or if the filmmakers just didn’t have the confidence to let the visuals speak for themselves. Ultimately it is impossible to lose yourself in the stunning 3D cinematography when you are constantly fighting back the urge to tell the characters to shut up.