THE 3D BLOCKBUSTER AVATAR had a $200 million budget and was rumoured to have cost at least twice that much to make.
James Cameron’s follow-up 3D movie, Sanctum, had a comparatively modest $30m budget, but this is a movie that has its feet firmly on, in fact under, the ground.
Sanctum, released on 4 February, is a cave-diving thriller but essentially a rites-of-passage movie, tracking the relationship of young diver Josh McGuire, played by Rhys Wakefield, and father Frank (Richard Roxburgh), in the aftermath of a dramatic cave collapse in the South Pacific.
The movie was filmed at the Warner Bros studio in Queensland, using dry-cave sets and a 40 x 40 x 7m-deep tank in which a cave system was built and then flooded. Studio footage was later intercut with real underwater cave footage from Mount Gambier.
Among a mainly Australian cast, only Welshman Ioan Gruffudd, who plays financier Carl Hurley, and Allison Cratchley (Judes), had done any scuba diving. John Garvin, the British technical diver who co-wrote Sanctum, was also the film’s diving co-ordinator, his task to lead the cast through a fearsome learning curve.
On completing their Open Water courses, the actors’ very next dive in the training pool was on a Sentinel closed-circuit rebreather.
“They actually took to it very easily,” says John. “But then they had to learn how to take the rebreather off, shove it through a body tube and swim after it. And when they’d got the hang of that, we turned the lights out and shoved them into an overhead environment.”
All the cast coped – in fact some, like Gruffudd, started turning up on their days off to log more hours on the Sentinels. “On a film set, where everything’s frantic and chaotic,
it was quite nice for them to disappear for a few hours in the pool.”
Rebreather training complete, the actors then had to master cave-finning techniques and use of reels, stage tanks, full-face masks, helmets, lights and DPVs. Why the intensive boot camp Because the actors would be diving the Sentinels in an overhead environment for real.
“Although safety divers were posted, it was the actors’ responsibility to monitor their own life-support systems while down there,” says John Garvin.
“If they got uncomfortable, they often couldn’t get out because they had a cave over their heads. It was as close to getting inside a real cave as any actor is likely to be.
“In most films, it’s very obvious that it’s stunt guys doing the underwater sequences, but many of the stunts in Sanctum were done by the actors.”
“You actually see Richard Roxburgh swimming through a tight body tube, and Richard and Allison at 7m dealing with a full-face mask flood emergency. And that’s a drill a lot of commercial divers baulk at, so to get actors doing that level of stunt was incredible.
“This gives Sanctum a high level of authenticity and realism,” says John.
“It contains underwater sequences that have never been seen on film before.”

AS A YOUNG ACTOR, John Garvin spent four years playing the lead in Buddy: The Buddy Holly Story. Following its West End run, the stage show went on a nationwide tour in the mid-1990s, playing in different locations every fortnight.
But John was leading a double life. “The tour was fantastic for me. I could go diving with the local BSAC club during the day and do the show at night.” While the rest of the cast and crew were lugging suitcases in and out of theatres, John was carrying twin-sets. His colleagues were intrigued, and asked him to teach them to dive.
John, five years into the sport, was a BSAC Advanced Diver. “I was brought up in Cornwall and would spend all my weekends snorkelling there, because I couldn’t afford the courses at Fort Bovisand.” Then he did a degree in theatre arts and “pretty much blew my entire first grant on dive equipment”. Remember student grants
Now John decided to become an instructor, and in turn train the Buddy crew so that they could join him on his beloved wreck dives.
“Before we knew it, eight of us were diving regularly,” he says.
The Buddy buddies’ passion would eventually lead them into trouble on a shore dive near Edinburgh. “It was my fault,” says John. “The tide had gone out and we couldn’t get back out of the water. By the time we’d swum about half a mile and climbed back over the fields, we were late for the opening.
“The curtain was held for 40 minutes, because I had the stage manager with me, as well as two Crickets! Diving was banned after that.”
In 1997, John became one of the first divers to train on Inspiration rebreathers. Two years later, he moved to Providenciales in the Turks & Caicos Islands and, spotting demand among visitors unable to obtain mixed gases for exploring the deep walls, set up O2 Technical Diving. He would run it until 2007.

DURING THIS PERIOD, John would also establish himself as one of the world’s foremost technical diving instructors.
He became both a TDI and IANTD Instructor Trainer for open-circuit and CCRs, and helped to arrange the first rebreather expeditions to Galapagos, Bikini, Truk and elsewhere.
He has done more than thirty 100-150m dives; was safety supervisor on Tanya Streeter’s 160m No Limits freediving record and on many underwater TV documentaries; and wrote the TDI Inspiration/Evolution training manual.
He even organised a submersible diving expedition to the Titanic. John Garvin knows about diving.
But his first cave-dive, in 2001, nearly ended in disaster. Cottage Pond on North Caicos is a 50m-wide sinkhole. “The locals believed in bad spirits that would suck anybody down into the bottomless caves and spit them out into the ocean.”
All John and fellow-Brit Mark Parrish knew about cave-diving came from Rob Palmer’s book Deeper Into Blue Holes. “We had a reel and some flashlights.
We didn’t have doubles, but in classic BSAC fashion we had little pony bottles and stage bottles.”
John describes descending into the sulphur zone where fresh water sat above the salt water of the deeper cave – this “awful primaeval soup”.
Vis plunged to zero, the divers’ skin was burning and they could taste rotten eggs. Emerging on the other side into icy water at 24m was like being “punched in the stomach.
“It was like some freefall parachutist dropping into St Paul’s Cathedral,” says John. “I shone my light around and couldn’t see the walls. It was an awe-inspiring moment – and later became the inspiration for one of the underwater sequences in Sanctum.”
The wall, when they found it, was “like a waterfall frozen in time; these incredible brilliant white speleothems pouring down it. It was stunningly beautiful. We did a full circle at about 30m above this dark void.”
Then, halfway back up through the mixing zone, John says: “I suddenly hit a solid wall and felt this gut-wrenching fear.” The divers had unknowingly dropped into the cave through a tiny fissure, and while reeling around the walls had wedged the line solidly into its thinnest part.
“My good old BSAC training came back – control your breathing; stay calm. I looked up and eventually saw a sliver of black that wasn’t quite as black as the rest of the black. I made sure Mark and I were connected, and we started floating up.
“I’d had three of the most intense experiences of my life on that 20-minute dive, from the elation of breaking through to a virgin cave to the fear of knowing I’d screwed up, and the relief of seeing blue sky again. I thought, if we got trained to do it properly, this could be a really cool sport.”
John and Mark undertook a full cave-diving course in Florida with the celebrated Tom Mount. This training led them and US diver James Hurley
to form the Caicos Cave Project, dedicated to exploring, mapping and raising awareness of the system.
“A lot of the experiences during this period fed directly into the script for Sanctum, in particular to the characters’ emotional journey,” says John.

JOHN GARVIN STARTED writing screenplays in his spare time and, after winning an international competition, had several scripts optioned by Hollywood producers. One, Sunless ea, was an underwater horror film set in a cave system.
The release of The Cave scuppered that idea, but the script wound up with producer Andrew Wight and executive producer James Cameron, who had been looking for a screenwriter with a cave-diving sensibility. They set up a meeting.
Australian Andrew Wight is not only a film producer but a renowned cave-diver. Back in 1988, he led an expedition to the remote Nullarbor Caves, during which a freak storm collapsed the entrance, trapping 13 divers underground for 24 hours.
Wight, who had collaborated with Cameron on 3D IMAX and TV films Ghosts of the Abyss, Expedition Bismarck, Aliens of the Deep and Last Mysteries of the Titanic, had always kept the story in mind for a screenplay.
“It’s obviously a surreal moment when you get a call to travel to LA and meet James Cameron and Andrew Wight to talk about your project,” says John. “Our 20-minute meet-and-greet turned into an eight-hour session where we just talked diving.
“Everybody knows James Cameron as the movie director, but he’s first and foremost an avid diver. I’m convinced he makes all these huge movies just to fund his diving projects.
“We started throwing ideas around about all the things that could go wrong on a cave-diving expedition. Andrew and I than went on to collaborate on the script of Sanctum.
“We saw absolutely eye-to-eye about the story. We didn’t want to make a documentary, because if done properly cave-diving is a very safe sport. Sanctum is a high-octane James Cameron roller-coaster of a ride, so we had to approach it from an entertainment point of view.”
The Fusion stereographic camera systems used for Avatar would be used again, but now the underwater director of photography Simon Christidis would have to move a camera housing “the size of a small fridge” around under water.
“3D is ideally suited to tight claustrophobic environments, and works very well under water,” says John. “However, the story still has to stand up on its own in 2D.” He welcomed director Alister Grierson’s decision simply to treat the shooting as if it were two-dimensional.
“While we’ve tried to be as authentic as possible, some compromises had to be made,” says John.
“For example, we used non-oral-nasal full-face masks so that the audience can see the actors’ faces, and so that they can speak to one another. We also had lights inside the masks, to help distinguish the actors. But nothing is used that couldn’t be used on a real cave dive.
“Divers will also appreciate that every plot twist relating to diving in Sanctum has happened on cave-diving expeditions. Ignore one problem and it builds into another – ignore that, and it compounds itself. British divers know this as the Incident Pit. Sanctum draws a lot on that idea, and I hope divers will recognise the truth of it.”
THE BEST WAY to get acting roles in Australia is to write them yourself,” says John Garvin. “In Sanctum I play Jim Sergeant, a bossy British dive instructor who walks around shouting orders at everybody, so it didn’t take an awful lot of acting on my part.”
As the time to start shooting under water approached, apprehension grew. Everybody was aware of how ambitious the concept was, and how tight the deadlines.
“The underwater shoots took place at night, over three and a half weeks,” says John. “We would work from 4.30 in the afternoon until 6 in the morning – up to nine hours under water at a time. We were all starting to look like albinos by the end of it.
“As with any dive expedition, it’s the stress of always looking for the what-ifs. Things went wrong, got delayed, didn’t go quite to plan, but that’s fine as long as you have back-up plans.
“I’m delighted that we decided to approach it all less from a film-maker’s and more from a dive-planning point of view.
“We had a model of the set, with little divers on sticks representing each character so that the director could show everyone exactly what the shot would involve. In the car park we ran guide-lines between cones and got the actors to walk through the shot.”
Wardrobe kitted the actors in wetsuits before they reported to the rebreather hut, where the five Sentinels would be prepped. “That was the one time I demanded peace and quiet while we took the actors through the pre-breathe.
“At the pool area their fins and auxiliary equipment were fitted, and they did all their last-minute checks.
The camera crew and lighting people were already set up in the pool, and when the actors got down they knew exactly what they had to do.”
John pays tribute to the “fantastic team of 20 very experienced Australian divers, who had either large amounts of CCR experience or had worked in the film industry and could share a lot of knowledge”.
The Sentinel rebreathers were rigorously tested by VR Technology’s Kevin Gurr and Phil Short in the UK before being shipped to Australia, along with Phil. Jason Blackwell was the local point of contact for the rebreathers.
“The Sentinels were a godsend,” says John. “They were extremely reliable, and the very bright green heads-up display and a buddy-monitoring display on the back ensured that the actors were kept safe at all times.
“Sentinels look like real warhorse rebreathers. We chose them for their reliability and ruggedness, but also because they look extremely cool.”

NOW SETTLED IN SYDNEY, John Garvin is working on two non-diving film projects, and enjoying the local diving. And he hopes Sanctum will have the same inspirational effect on a new generation of divers as The Deep and Cameron’s The Abyss once had on him.
“Cave-divers get criticised, but the film explores the emotional attachment we have with caves, and why cave-diving is like no other sport.
“Cave systems are our last unexplored wilderness, and there’s nothing as incredible as being able to shine your light where nobody’s been before.
“I hope Sanctum will serve as a tribute to all those people who have been pushing the boundaries of the sport.”

Meet John Garvin in person when he guests at LIDS 2011 in March.