In 1960, a U.S. Navy submersible craft, called the Trieste, plunged almost 11 kilometers to the deepest part of the Pacific Ocean off the coast of Guam.

For more than 50 years, that pioneering record in ocean exploration has not been broken.

Now, explorer and film director James Cameron, who won an Academy Award for the motion picture "Titanic," is repeating that record-setting journey. He's doing it solo, in a unique, torpedo-shaped submersible, a one-person craft he helped design with a team of engineers over the past eight years.

Unlike most submersibles, the tiny sub is oriented vertically. And it uses lighter materials like super-strong structural foam to improve buoyancy and to withstand the enormous deep-sea pressures.

Cameron hopes to unlock a few more mysteries about life at the ocean bottom.

"We know very little about the species that live down there," Cameron says. "We know little about the distribution of the biological communities. We don't know know how these animals have adapted to this unbelievable pressure that exists down there."

Cameron will film and collect samples on the seafloor for about six hours before returning to the surface.

Going deeper than Mt. Everest is high

Cameron's mission will owe much to that pioneering dive, more than a half-century before, by the crew of the Trieste.

When co-pilot Donald Walsh first saw the Trieste on a flat barge in San Diego, California, more than 50 years ago, he wasn't impressed. "It looked like an explosion in a boiler factory. And I looked down at all these bits and I thought, 'Good luck to them.' I couldn't make any sense of it."

What Walsh, then a Navy lieutenant and aide to the commander of a fleet of submarines, didn't know at the time was that he would co-pilot the Trieste.

The mission would advance ocean science by taking the craft to the ocean floor at a depth of 11,000 meters - deeper than Mt. Everest is high.

"That was more than 10 times deeper than I had ever been in a submarine," he says. "Most oceanographers don't like excitement and adventure. They want a very stable, reliable, well-known platform. What better demonstration of the safety of this platform than to go to the deepest place in the ocean and come back perfectly intact and in working order?"

The Trieste is a bathyscaphe - a free-diving self-propelled submersible - one of just two in the world in the late 1950s. It is an impressive craft at over 16 meters long with a gasoline-filled flotation chamber's deck, rails, and conning tower that make it look a bit like a submarine.

"Basically, it's an underwater balloon," Walsh says.

"You've got two parts to it: You've got the balloon - which is (a) long cylindrical object - and that's filled with a lighter-than-water substance, which is aviation (grade) gasoline. Oil floats on water, and so you get the buoyancy or lift. Then beneath the balloon you have a cabin for the fragile humans."

On Trieste's historic dive, the co-pilots would be Walsh and Swiss scientist Jacques Piccard - whose father, Auguste Piccard, had designed the craft.

In late December 1959, Walsh recalls, he and Piccard headed to Guam to begin a series of test dives. "By the time we got to January 1960, we were pretty familiar with the workings of the submersible."