Two parts Hydrogen and one Oxygen; James Cameron’s recipe for disaster

As a keen diver himself, Cameron was keen to work on a project that brought the audience into the world of diving. Previous big water-based pictures such as The Abyss and Titanic had seen massive commercial and critical success, with Titanic becoming the highest grossing film of all time, superseding any film budget seen before with $200 million spent on its creation.

One of a handful of directors known for producing box office gold, there was an enormous hype for Cameron’s last film Avatar, and the effects certainly didn’t let down. He’d had the vision for Avatar by the time he’d completed Titanic but the technology required didn't exist, so Cameron set about creating it. It’s that same technology that has been used in Sanctum for the complete 3D effect.

Sanctum follows a team of underwater cave divers on a hazardous expedition to the largest, but least accessible cave system. It's never been previously explored, so when a storm leaves them trapped in the unknown cave they have to search for an escape with limited resources.

The 3D effects allow you to become completely immersed in their situation, to the point where you feel the raindrops could fall on you.

It's inspired by the true events of writer Andrew Wight, who led a cave expedition in 1988 beneath the Nullarbor Plain in Australia. A storm led to the entrance collapsing leaving himself and 14 others trapped. Fortunately everyone survived due to a rescue team, but the characters in Sanctum are not so lucky.

The film is bursting with suspenseful scenes and certainly takes you on a journey with the characters, hoping for their survival all the way. They all have obvious flaws, and a significant point is made about having to be selfish at a certain point in such dangerous scenarios. It might seem harsh, but one life lost is better than two.

Having tried a taster experience at the London School of Diving, I’ve been taught key rules of diving. If you haven’t tried, it’s undoubtedly an unusual experience - but if you can get used to breathing only with your mouth - a worthwhile one. You’re taught that it’s vital to keep breathing at all times and not hold your breath or become stressed - easier said than done when underwater, knowing that if your oxygen supply is cut off you’ll have a matter of seconds to live.

Another risky element to diving is the speed in which you descend and ascend from the water; too quick on the way down means your ears won’t equalise and you’ll have a nasty headache and too quick on the way up and you’ll experience “the bends” or Decompression sickness - bubbles forming in the body which can be fatal.

With cave diving, there are extra factors beyond human control that you can only best prepare for, particularly in exploring new territory. The film addresses all of these features well, and incorporates an array of disasters to keep the audience hooked. You share their panic in moments of desperation trapped under water, with some gory shots thrown in which only highlights the risks they're taking.

Richard Roxburgh's exceptional performance almost makes you forget the few cheesy moments or awkward dialogue. It might be a little "Hollywood" at points, but my only criticisms would be of Ioan Gruffudd’s American accent and the cheesy voiceover at end – it was kind of implied guys, no need to spell it out to us.

The claustrophobic sense of the film is integral to its success. Wright’s co-writer John Garvin said “I tried to bring that sense of claustrophobia to the audience, and of course it being a 3D movie, that lends itself perfectly to this type of film.” A good 3D film will allow you to forget that it’s even in 3D and after about 20 minutes into the film I certainly forgot about the glasses.

Perhaps Cameron just really wants us to develop a fear of water so he can keep the great diving spots for himself. He's widely regarded as a bit of a tyrant on set, but his passion for his features is always clear, having dove the Titanic and the Bismarck himself for research on ocean documentaries.

For Titanic, it was widely reported that Cameron had the actors stretched to beyond their capacity, leaving many ill and injured during the demanding filming schedule. Kate Winslet, who broke a bone during filming, said she’d have to be paid a lot of money to work with the director again. As Executive Producer behind Sanctum, the project had similar expectations of the actors, where they carried out a lot of their own stunts:

“It’s amazing to think that many of the underwater stunts you see in the film were done by the actors themselves." said Garvin. "Removing a rebreather and pushing it down a tight body-tube? The actors did it. Buddy breathing with a flooded full-face mask? Richard Roxburgh and Allison Cratchley nailed that stunt.”

Director Alister Grierson was chosen for the job due to his success with Kokoda, a true story about a platoon of soldiers lost in the jungle. The film was produced on a small budget and managed to become one of the top five grossing Australian films in 2006. Although he’s relatively unknown in the industry at the moment, with a big name like Cameron’s backing Sanctum it’s unlikely that will be the case for long.

Let’s hope he doesn’t develop too many of the same tyrannical tendencies as Cameron. But if he did, you might just think it was worth it.

Sanctum is released in cinemas 4 February. To experience a taster course in scuba diving, visit www.londonschoolofdiving.com