James Cameron's assistant tries to distract him one more time – he is an hour late for an appointment – but he can't be stopped. Even when Cameron finally apologizes and says that he must go, I have to ask only one more question about the last hours of the Bismarck, the legendary German battleship, and he is up on his feet, colored felt-tip pens in his hand, drafting diagrams and schematics on the large board that runs along the meeting table in the Santa Monica offices of his production company, Lightstorm Entertainment ... drawing out the ship's construction, its armor belt, the "armored citadel" within it, the offset stairways ... sketching missile trajectories, torpedo paths, and listing angles ... exhorting the merits of plunging fire ... telling of the Swordfish torpedo that initially slowed the Bismarck and compromised its rudder with a one-in-a-million shot ("A great story! It's like Luke Skywalker attacking the Death Star!") ... and on and on, entranced by his own excitement at what he knows, and what you do not. His words are those of a smart, persuasive storyteller, part prosecutor, part scientist, clearly fluent in a wide range of disciplines, but his body language is that of an excited child in a bathtub, playing with his battleships.

Although he has dipped his toe into television by producing the sometimes-engaging, now-canceled Dark Angel, James Cameron has not made a feature film since 1997's Titanic, the most successful movie of all time. His next movie project will be announced before the end of the year, he says, but he has been concentrating on other adventures. This summer, for instance, he visited the Bismarck's wreck and became the first person to guide cameras inside the ship since it sank, in May 1941, with the loss of more than 2,000 German lives; a two-hour documentary airs on the Discovery Channel on December 8. At one point in our conversation, I mention that the keenest fans of his work, as much as all this interests them, might be wondering why he is not making movies.

"Because," he retorts, "I'm not living my life for them." And exploration is what has possessed him recently. "Hey," he says, "I was a wreck diver before I was a filmmaker. As far as I'm concerned, there are plenty of wrecks out there. And every wreck is a story. I've been doing this for 25 years, and I could do it for the next 25."

James Cameron was born in Canada 48 years ago, the oldest of five children. For most of his childhood, he grew up in Chippawa, just upstream from Niagara Falls, where his father worked as an electrical engineer at the local paper mill.

One day, when James was in grade school, his mother took him to the Royal Ontario Museum, where he saw an underwater habitat built by a Canadian scientist named Joseph MacInnis. It was called Sublimnos, and MacInnis was using it in the Great Lakes. It was large and yellow, and Cameron stared at it for a long time, while his mother kept trying to get him to go because they were going to miss the bus. "I understood exactly how it worked," he says. "There are certain moments when you just get it, and then you have to do something about it. You have to act."

Back home, he drew pictures of Sublimnos, then began working on his own version with his brother Mike, who's two years younger. The two were always building things: an elaborate tunnel system that ran under the neighborhood, model rockets they fired into the sky, a hot-air balloon made out of dry-cleaning bags and fueled by candles, which is said to have roused the attention of the fire department and appeared in the local paper as a possible UFO. The Cameron brothers, even then, were sometimes partners, sometimes rivals. "I was usually the instigator of the plan," Cameron says, "and Mike would sometimes go along with it. Or sometimes it would be a younger-brother competitive thing, and he would have to go and do his own plan."

For his Sublimnos project, Cameron used a mayonnaise jar, pieces of his erector set, and his pet mouse. He wanted to prove that life underwater was possible. He and Mike put the mouse in the jar, hung the contraption on a rope, and lowered it into Chippawa Creek. "The mouse went to the bottom of the river, sat there for half an hour, and then came back up," he remembers, and he still seems rather satisfied by this.

Young James was a dreamer, obsessed by science fiction films, as many boys are. "I especially loved films about exploring other planets," he recalls. But unlike other kids, he was always focused on ways of making his dream world come true: "I was never satisfied to just live in my head. I really wanted to go and do those things." This was the heyday of the space program, in the late sixties, and there was nothing cooler than being an astronaut. Cameron figured that, realistically, the odds were stacked against his ever getting to space, so he set his sights on something more attainable: going downward. Although he lived 400 miles from the ocean, when he was 15 he pestered his dad to let him take scuba-diving lessons. He dived in the only places he could, in the local lakes and streams. "With the ducks," he says.

As an adult, Cameron became a successful film director. His family had moved to the U.S. in 1971, and he studied physics at Cal State Fullerton. But he dropped out before graduating. He'd wanted to make films ever since he was a kid watching 2001: A Space Odyssey over and over and shooting amateur movies with homemade special effects on his father's super 8 camera. But he had short careers as a machinist and a truck driver before he got a job making models for low-budget exploitation filmmaker Roger Corman. He took what he learned there and established himself by writing and directing The Terminator in 1984. He developed a reputation for his potently brash, emotionally simple (and strangely romantic) effects-heavy movies – Aliens, The Abyss, Terminator 2, True Lies – and for his forceful personality: a bullying, egocentric bighead to those who didn't like him; a focused and forceful visionary to those who did. Even during his greatest moment of triumph – Titanic's 11 Oscars at the 1998 Academy Awards ceremony, when he stepped to the podium and hollered, "I'm king of the world!" – what many saw as the understandable celebration of a talented man getting his just reward for his obsessive, glorious labors, his detractors saw as a perfect example of the gracelessness and insensitive egotism they witnessed in both his working practices and the work itself.

In the meantime, Mike Cameron forged a career in aerospace technology, but over the years his older brother would call on him to help with his film business more and more often. The movies James Cameron wanted to make always seemed to require technical innovations and inventions that made possible something or other that had never been done before, and Mike was up to that kind of challenge. One can't help thinking that it's the very essence of James Cameron's nature to want what doesn't yet exist. As he puts it: "I have a hard time finding the exact line between fantasy and reality. I don't mean in any kind of delusional sense. I just think that if something is worth thinking about, it's worth doing."

It was in 1995, when Cameron set his mind on exploring what he calls "the ultimate shipwreck," the Titanic, that the two of them took on their first major technological challenge. The ship lay about 400 miles off the coast of Newfoundland, 12,500 feet beneath the ocean's surface. Previously, people had filmed 35mm motion-picture footage at such depths only by shooting through the windows of submersibles. But Cameron wanted a camera outside the submersible so that he could pan it and tilt it and move it around as if it were in his hands. He approached people in the maritime community and was told it was impossible. "They seemed a little know-it-all and standoffish," he says, "and I just had this basic kind of truck driver's sense that it can't be that hard."

Mike, of course, agreed to try. They shrank the camera and then fitted it, as James says, "in a big-ass can with a really thick titanium wall" to withstand deep-sea pressure. Cameron's interest in the camera's success wasn't just financial or technical. A camera casing that imploded next to the submersible could kill them. "It would be like setting off a few sticks of dynamite right outside the window of your submersible," he explains.

He went on the first dive, two and a half hours down, the pressure slowly rising to almost 6,000 pounds per square inch. By 500 feet, it was pitch-black; the lights had to remain off to conserve battery power. The only hints of life were the occasional purple, pink, or blue iridescent trails of passing bioluminescent organisms. Cameron and two pilots sat squashed into a seven-foot sphere, heated by nothing but the craft's electronics and their body heat, condensation dripping from the walls. Down, down, down ... until, as Cameron would later recall with characteristic melodrama, they came upon the Titanic so quickly that they nearly crashed into it. The camera casing, however, was fine.

Over the next few weeks, they went down to the wreck 11 more times to get footage for the movie. Their exterior camera was encased in a large, 200-pound ROV (remote-operated vehicle) that was attached to the submersible by thick cables, meaning it couldn't roam inside the ship without running the risk of being snagged and lost.

On one of their last dives that year, however, Cameron took the risk and guided the camera inside the wreck. It couldn't go far, but it went in about 15 feet, just a little way down the grand staircase, far enough that he nearly didn't get it out again. (Most of the movie's footage of the underwater interior was shot on a set in Mexico, constructed by using the original manufacturer's detailed blueprints and a bit of imagination.)

The expedition was a success; the movie it spurred even more so. (It grossed $1.8 billion worldwide.) But that wasn't enough for James Cameron. In the back of his mind, it was driving him crazy: what he had seen down in the wreck, and what he had nearly seen. "It was dark," he remembers, "but in the dark was a deeper darkness, and just at the end of the lights you could see it." Something just out of reach of what was possible, just farther down the hall than anyone could see. "And I thought, Wouldn't it be cool to go down that hallway?"

It's these missions – on the edge of ambition and science and safety and possibility – that seem to most excite Cameron. I ask him what it is that he gets from being down there, under the sea, doing something no one has done before.

"I'm living the fantasy," he says. "And the fantasy is that I'm living in a science fiction story. I'm at the cutting edge of technology, I'm exploring, I'm in a little spacecraft and I'm seeing something that no one's ever seen before. I'm not just along as a visitor. I'm part of the process. I'm a crew member on the first human expedition to Jupiter. That's how I see it."

In following these passions, Cameron believes, he is simply fulfilling a

basic biological drive, one that many people have been distracted from. "I think exploration is a fundamental aspect of the human character," he says. "And I think as a culture we have sort of reached a point where we view exploration as a kind of extreme sport, like bungee jumping, with no greater value. But in fact, if you look at the history of human civilization and our survival to this date, and our accomplishments, the cultures that were dominant were always the ones with the strongest exploratory nature: the British, the Spanish, the Dutch, the Portuguese. You know, these are the cultures that have become technologically dominant, and therefore economically dominant."

I ask him whether he consciously thinks he's doing his bit for the future prosperity of North American civilization.

He laughs. "I don't give a shit about that," he says. "Not at all. I couldn't care less." For Cameron, his filmmaking is the excuse that justifies his exploration. "I think that it's much easier to find a moral justification or an ethical justification for going and doing these things if you're bringing the experience back, and you're sharing it," he says. "Let's say I want to spend $50,000 to have somebody guide me up Mount Everest. Mount Everest has been climbed. We have pictures of it. There are oxygen bottles lying all over it. To do that is to give oneself a $50,000 present of an experience. It's not something that gets shared with the human race."

When Cameron visited the Titanic for the first time, back in 1995, he said it was to collect footage for the movie. He now swears that the truth was the other way around. "I don't think the studio executives believe it, but I wanted to make Titanic because I wanted to dive the wreck. I thought: How can I dive the Titanic and get somebody to pay for it? I'll make a movie."

So, I clarify, the biggest-grossing movie in motion-picture history is just a little side effect of a personal whim?

"Exactly." He reconsiders the question, as though pondering whether I have somehow slighted him. "It's not a whim," he objects. "A whim implies 'I think I'll go play pool tonight.'"

Quest, then.

"Quest," he agrees. Quest is a much more James Cameron word. "That's good," he says.

After all the hullabaloo of making Titanic was over, the Cameron brothers, along with a few friends, went to the Bahamas on vacation, on a dive trip to feed sharks. It was there that Cameron began to talk about how he was going to be able to see more of the inside of the Titanic (which, it was already obvious to him and anybody who knew him, would have to involve making some kind of new film).

What they needed was a much smaller ROV that could be launched from the submersible, one that wouldn't stir up the 90 years of delicate silt "as fine as cigarette ash" that had collected in the Titanic, and would be able to avoid the five-foot-long stalactitelike rust formations that, with no more than a bump from the camera, could crumble into clouds of red and turn the whole experience into something "like diving inside a bowl of minestrone."

The breakthroughs came slowly: building the vehicle's frame out of something called syntactic foam, the only known solid that's buoyant at a depth of 12,000 feet; using battery power for the ROV; using a much thinner filament to deliver control instructions to the ROV and download footage; overcoming the microfractures caused in parallel fibers at that pressure by suspending them in a thixotropic gel ... Cameron gets so excited talking about this stuff that soon you're nodding with near-thrilled agreement at each new ingenious solution. It's only later that you realize you have not even the faintest idea what a thixotropic gel might be.

Cameron decided to use these new ROVs – they built two of them and named them Jake and Elwood – to make an Imax movie about not only the Titanic but also the Bismarck, which sank 400 miles southwest of Ireland during World War II. Though Cameron would become as passionate about the Bismarck as he is about the Titanic, at this stage it principally offered a nice counterbalance as another deep-water wreck that had been discovered but little explored. When it was launched, the Bismarck was the largest battleship on the world's seas, and, like the Titanic, was considered unsinkable. But on its first mission, it was engaged by British ships and planes, harried, and – after a chain of events much debated by historians – sunk. Of the estimated 2,200 men on board, 115 survived. The film based on Cameron's new footage of these two wrecks would be called Ghosts of the Abyss. Before visiting the wrecks, he interviewed Bismarck survivors in Hamburg.

Then, in August 2001, he finally returned to the Titanic and guided the ROVs inside. His fantasy was becoming a reality. "That was a strange experience for me," he says. He had been through these corridors before, on the set he had built in Mexico. "I would turn a corner, projecting my consciousness into the ROV, and I would know what was going to be around the corner – the number three elevator on D deck – and I'd come around the corner and there it would be. And I had been in that elevator. Or a simulation."

James Cameron was at the bottom of the ocean at the wreck of the Titanic, on the ninth of his team's planned 12 dives, when a message came from the surface that something very bad had happened. It was September 11. The Bismarck expedition was postponed. Ghosts of the Abyss (which is now due in Imax theaters around April 2003) would focus on only the Titanic.

Not long after Cameron and his colleagues got home, they began to work out how to continue the Bismarck project. The Discovery Channel agreed to finance a two-hour television documentary, James Cameron's Expedition: Bismarck. "I tried getting somewhere with the other established natural-history expedition people – not naming any names – but they were dicks," Cameron says. "They were dicks. They just didn't get it. 'Oh, we don't do it that way. Show us your script and we'll think about it.' Fuck you. We're going to go and do something really cool. Then we showed it to the Discovery people, and they said, 'Hey, this is really, really cool.' "

Andrew Wight, who produced Ghosts of the Abyss and Expedition: Bismarck, and who has made many documentaries with both the Discovery Channel and the longer-established

National Geographic Society, suggests: "I think there was probably more of a potential for a pissing match with NGS. Discovery was quicker

to defer to Jim's judgment and experience as a world-class filmmaker. I don't know that he would have gotten the same latitude from NGS to do what he has done."

The expedition arrived at the site in the ocean 16,000 feet above the Bismarck's wreck on May 27 of this year, the 61st anniversary of the ship's sinking. The two German survivors they had brought with them, Walter Wentz and Karl Kuhn, threw a wreath from the back deck into the gray, rolling ocean. Two days later, Cameron did the first of six dives.

For Cameron, going inside the Bismarck was a very different experience from the Titanic. For one thing, he didn't know what was going to be around the corners. "The Bismarck had a much more threatening feeling," he says. "It felt grimmer. I mean, there's a romanticism around the Titanic. And you know when you're exploring those spaces in the bow, the dining room, you can appreciate them for their past beauty. But they're not in and of themselves the scene of the death, because most of the people evacuated abovedecks and went into the water or got to the stern. In the Bismarck, you're surrounded by death everywhere you look."

To get approval for filming, Cameron promised the German government that his crew would not be disturbing any human remains. Cameron's team argued that in high-pressure, low-calcium water, aided by opportunistic deep ocean bacteria, the bodies would have long since dissolved. When you die like this, everything dissipates over decades except whatever leather you were wearing. "What you get is – it's like something from a science fiction movie – there will be a set of clothes there," Cameron explains, "and the shoes."

From their dives, Cameron and his people pieced together what happened to the Bismarck in its final hours, and much of Expedition: Bismarck will deal with evaluating such evidence, particularly in relation to whether in the end the proud Germans scuttled the ship, as survivors have claimed. (Cameron's conclusion seems to be that they did, and that, though the ship would have sunk eventually, it was the scuttling that directly dragged it down.) Just as in his movies and in his life, Cameron is prepared to challenge the line between fantasy and reality in order to dramatize the truth as he sees it: He filmed a week of reenactments with about 25 actors in North Carolina.

His brother Mike was involved throughout the expedition, and they both have big plans for the groundbreaking new ROVs. In fact, when this story was first being reported, Mike agreed to take me out off the California coast to explore a wreck with one of the ROVs. Then word came that the brothers had fallen out, and Mike would no longer cooperate with the story. It was then that I recalled the look on James Cameron's face when we had been discussing his turbulent youthful collaborations with his brother. "It's always been like that," he had said, and smiled; maybe the falling out had already begun by then. "And the psychology of that persists today."

"That's called families, and that's called brothers," says Wight, who sometimes flies helicopters with Mike for fun on his days off from working with James. "One week they're not talking, the next week they are. And when you're close in age and you have one brother who has done exceedingly well publicly, and you reckon ... and you probably are as smart if not smarter ..." He stops and reconsiders. "Sibling rivalry, at any age, doesn't care whether there's someone wanting to do an article on you."

Wight describes how the Cameron brothers work together: "One will propagate an idea and then, like a terrier dog, one will pick it up and run with it and then claim it as his own and develop it, and then it'll bounce back to the other for more refinement, which usually results in the first major argument. It can be adversarial – they really push each other to the limit... . If you ever meet Jim's mother, she's quite a card when it comes to talking about Mike and Jim – she just wants to knock their heads together and make them grow up."

In recent years, the ambition Cameron abandoned as a child – when he decided to go down into the oceans rather than dream of space – resurfaced. He began talking to the Russians about visiting the Mir space station and making a film there. He went through the biomedical screening process in Russia for six weeks so he could qualify for cosmonaut training, and was negotiating to do a Soyuz launch to take him to the space station. When Mir was allowed to burn up during reentry in 2001, Cameron started investigating the only alternative, the International Space Station, and sought NASA's cooperation.

"We actually hammered out an agreement under the Space Act to develop a filmed space mission," he says. "It didn't mean they'd agreed. It meant that they wanted to explore it." Cameron had been planning to live in Russia for 18 months to go through the full cosmonaut training, because he wanted to be the first noncareer astronaut to spacewalk, and to take a camera with him. After September 11, he put the project on hold. He now intends to investigate a simpler mission: using an astronaut as a cameraman and directing him from inside the space station.

I ask him about Lance Bass, 'NSync's wannabe spaceman. Cameron approves; maybe he knows what it's like to be dismissed as a populist with overgrown dreams. "People are going to make fun of him, say, Oh, this is frivolous," he says. "Now, Lance Bass is going to go and have himself an experience. But what's the good that comes from it? You've got a bunch of kids who look up to this guy, and he's not some rapper with a bunch of gold chains and a big white Cadillac, squandering his money. He's saying, All right, I've got a lot of money now. What am I going to do? Get a bigger house? Buy a jet? No, I'm going to go do something that I think is important, something that all of this wealth, all of this American dream, doesn't give me." To Cameron, it's missions like these that lift us onto the first rung of the ladder to exploring the rest of the universe. "We're not going to go out there and meet all those cool alien civilizations and see other planets if we don't take the first step," he says. He's unstoppable now; I guess this is the James Cameron many love, and some loathe: forceful, evangelical, and entirely without self-doubt. "Learning to live in space for long periods of time is the true first step. Going to the moon was a sprint. Those guys were up there for only eight days. I can put up with anything for eight days. To go to Mars, the nearest planet that we can land on, that we could possibly physically explore and walk around on, the only one that stands any chance of being Earth-like enough to ever sustain life in some form, would take two to two and a half years – unless we have some huge breakthrough in propulsion."

Would you go?

"Mmmmm," he says. "Well, that's an interesting question. And it is something that I have my characters in my Mars story [one film project he is working on] struggling with, because when you have a family ..." He laughs at this pretense of weighing the pros and cons; he knows we both know the answer. He can't, and he won't ... but given the slightest chance ...

"Absolutely."