He is taking forward his penchant for the fighting spirit in his forthcoming 3D underwater thriller "Sanctum". But Hollywood producer James Cameron says filmmaking is not about the equipment but about images and imagination.

"The cameras used on 'Sanctum' included the same cameras developed for and used on 'Avatar'. The team knew that if they were to fully immerse the audience in the underwater world, it had to be in 3D," said the three-time Oscar award winner.

"Along the way, the men developed a new photographic system that could operate in these extreme environments and deliver a cinematic experience. But as mind-blowing as all this new technology is, filmmaking is not about the equipment. It is about ideas, images and imagination. It's about storytelling," Cameron told IANS in an e-mail interview.

He said audiences will experience a different ride in "Sanctum" compared to his magnum opus "Avatar".

"'Avatar' had so many broad vistas that the difference between watching the movie in 2D and in 3D is not that great because the more expansive the image, the less you feel in close contact with objects and characters.

"The difference between experiencing 'Sanctum' in 2D and in 3D is actually much greater because the 3D will constantly be informing you, in the experience of watching the movie, with the sense of claustrophobia," said Cameron, 56.

"We've done test screenings and we've seen that there's a palpable, white-knuckle sense of anxiety in watching the movie, which is exactly what we wanted to create. Usually, when you go to a movie, your consciousness floats above the film. 3D sucks you in and makes it a visceral experience," added the 3D technology's greatest advocate.

Both "Avatar" and "Sanctum" have been shot on the Cameron/Pace Fusion 3D Camera System, a stereoscopic HD camera system that delivers incredible results that can deliver flawless IMAX projection in 3D.

Directed by Alister Grierson, based on the real life story of writer-producer Andrew Wright, the film is releasing worldwide Feb 4.

Shot on location at Gold Coast in Queensland, Australia, the 3D epic underwater adventure follows a team of underwater cave divers on a treacherous expedition to the largest, unexplored and least accessible cave system on Earth. When a tropical storm forces them deep into the caverns, they are compelled to do nothing but fight raging water, deadly terrain and creeping panic as they search for an unknown escape route to the sea.

"With 'Sanctum', we want audiences to be left with a certain experience where they feel involved with the perils faced by the characters... It's not action like in an 'Indiana Jones' movie or even in a thriller where you have fight scenes and gun play," he said.

"It ('Sanctum') is really about the psychology of survival, and of people stretched right to the edge of what they can stand, and then beyond. I love that kind of story, personally. It doesn't need all the bells and whistles to be powerful," he added.

Cameron is also gaga over the unprecedented buzz for the movie in India.

"I am so glad that 'Sanctum' is being received so well in India when the film is on the brink for release. The film is, more than anything else, a story that needed to be told," he said.

Not many know that Wright and Cameron are long time collaborators.

"Andrew and I had previously been on some great adventures together. We dove deep into the ocean to uncharted depths to explore and discover never-before-seen parts of the ocean floor and marine life for 'Aliens of the Deep'. We dove the 'Titanic' (for 'Ghosts of the Abyss') and the 'Bismarck'," he said.

In terms of future projects, Cameron is "tied up for the next five years" as the filmmaker has "signed on for two more 'Avatar' films".