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.