James Cameron: Deep-Sea Director
Credit: Mark Theissen / National Geographic

In January 1960, a U.S. Navy submersible carried two men to Challenger Deep, the bottom of a trench seven miles below the surface of the western Pacific – the deepest point in the world's oceans. They stayed for only 20 minutes, but it was enough to captivate a boy from landlocked Chippawa, Ontario. "I couldn't think of anything cooler than being a deep-ocean explorer," says James Cameron.

In April 2012, after working in almost total secrecy for seven years and ahead of other high-profile teams, including one backed by Virgin tycoon Richard Branson, Cameron became the first person to return to Challenger Deep since 1960. Now the underwater expedition is the subject of a documentary, James Cameron's Deepsea Challenge 3D. The journeys of Cameron's electric-green "vertical torpedo," Deepsea Challenger, were dogged by calamity – bad weather, failing equipment, and the deaths of his colleagues Andrew Wright and Mike deGruy, who were preparing to film the expedition when their helicopter crashed.

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Even Cameron's dive in Challenger Deep was cut short. After less than three hours on the bottom, the sub's thrusters and the hydraulic manipulator arm used to collect samples succumbed to the pressures of more than 15,000 pounds per square inch, and the craft could be steered only in circles; another submersible at that depth had imploded from the overwhelming pressure in May, disappearing in less than a second. Only then did the director face the most uncertain moment of his trip. "Anybody can get down to the bottom of the ocean," Cameron says. "People have been doing that for thousands of years. It's getting back up that's the hard part."

When you first dreamed of going to Challenger Deep, what did you imagine you would see once you reached the bottom?
When you're a kid, you imagine giant squid, lost civilizations...Now I know not to expect that sort of thing.

Were you disappointed by what you found?
Not at all. You see some jaw-dropping things a couple of miles down, but we knew that at the bottom of these trenches life would take subtler forms. We eventually found evidence of hydrothermal activity. That was a breakthrough, but we only scratched the surface.

What did your wife [Suzy Amis] say when you first mentioned doing it?
She never said, "Don't do it." We had an understanding. She's a pilot and an extreme skier, and she knows that you need to follow your passions. So when I told her I was doing the bottom-of-the-ocean thing, she didn't bat an eye. Now, there's a difference between that moment, long before it's actually real, and her being out there on the ship. She was under a lot of internal stress, but she would rather be there on the ship than at home, waiting for a phone call.

Is this the most dangerous thing you have ever done?
Oh, no. I've done a lot more dangerous things. I've almost drowned a couple of times. I've done cave diving. I've flown jet aircraft. I've filmed shark feeding frenzies. I used to be a street racer when I was younger. So I guess I just didn't think of it as that dangerous. I acknowledged that there are always things that you don't think about. Until recently, only two vehicles were able to reach those depths and drive around. One is our sub. The other – the Nereus from Woods Hole Oceanographic Institution – imploded a couple of weeks ago.

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You originally planned to be sealed inside the submersible for nine hours. Did your design include any sophisticated toilet facilities?
It wasn't very sophisticated. Basically a pee bottle. And Number Two was right out. That's just not done.

Were you worried when your craft malfunctioned on the ocean floor and you couldn't steer well?
About two hours were cut off the bottom dive because capability ran out. I could have stayed down there. There was no problem with life support, but I just couldn't do anything, so it didn't make sense.

You have a reputation for being demanding on film sets. Do you handle an expedition team differently?
With the expedition stuff, it's not just about putting the pedal to the metal and pushing people – it's about keeping them alive, safe, and motivated. Yelling at people is counterproductive. And I definitely have a different leadership style now as a director than I did in the Terminator days. My philosophy used to be, if we don't get to the bottom of why this mistake happened, it's just going to happen again. So I would be merciless if someone screwed up. I don't do that anymore. Now I just roll up my sleeves and say, "All right – what are we going to do to fix it?"

When can we expect to see you make a film in space?
I was planning on doing that in 2000. I was well down the path. We were testing the cameras. I'm less interested now, because what does space mean? Until we get our finger out of our butt and start thinking about sending human beings to Mars, I'm not that interested in the International Space Station. It's as if Columbus, instead of going to America, parked his boat outside the harbor and said, I'm going to study the problem of living on a boat for the next 40 years. That's where we are right now.

Would you rather be remembered for doing this or as the director of Titanic?
I like the exploration stuff more. Now, often as not, I'm introduced as explorer-filmmaker, as opposed to filmmaker – it's gone from a hobby to being perceived as a primary focus. So I like that better. Though I'm too young to be thinking about legacy. I got too much shit to do.