On March 26, 2012, National Geographic Explorer-in-Residence James Cameron made history by becoming the first person to make a solo dive to the deepest known part of the ocean, the Challenger Deep in the Mariana Trench, nearly 11 kilometers (7 miles) below the water’s surface. Cameron used an innovative, sophisticated submersible, the DEEPSEA CHALLENGER.

Fifty-two years earlier, in 1960, U.S. Navy Lt. Don Walsh and Swiss oceanographer Jacques Piccard reached the Challenger Deep in a submersible called the Trieste. Piccard died in 2008, but Walsh is still involved in ocean research and was a key adviser on Cameron’s team.

Designed by Piccard, the Trieste looks vastly different from the DEEPSEA CHALLENGER. The DEEPSEA CHALLENGER resembles a rocket—a narrow, vertically oriented tube. The Trieste, in contrast, was designed like a hot air balloon, with a cylindrical top section composed of a float filled with gasoline and water to lift the vessel back to the surface after the dive. Attached to the bottom of the Trieste was a small, pressure-resistant sphere with enough room for just two people.

“I think [the Trieste’s design was] pretty much a free balloon that would fly in the sky—except the balloon part was sausage-shaped rather than spherical because that’s an easier shape to tow,” Walsh says.

He was impressed by the simplicity of the vessel’s design.

 “It’s like the paperclip or can opener. Everybody thinks, ‘Why didn’t I think of that?’” he says. “Once you look at it and see it, you realize it’s pretty simple.”

Walsh is quick to note that the DEEPSEA CHALLENGER is far more technologically advanced than the sub he and Piccard used.

“People ask me what were the differences between the Trieste and the DEEPSEA CHALLENGER. That’s like asking Orville Wright what was the difference between your airplane and a 747,” he says. “They both do the same essential job. They carry people down to the deepest place in the ocean. They are capable of withstanding great pressures. But there, most of the similarities end, because you are talking about a half century of technology.”

Some features of the DEEPSEA CHALLENGER—including its lights and cameras—would have been beneficial had they existed in 1960.

“We didn’t have very good stuff then,” Walsh says. “Nothing existed. If you needed something, you had to design it and build it. There were no catalogues or companies that specialized in providing components for deep submersibles.”

For Walsh, the DEEPSEA CHALLENGER is a perfect example of the whole being greater than the sum of its parts.

“There’s lots of it,” he says. “But it’s the way it all came together, the final design and configuration of the thing.”

Spanning a Generation of Exploration

More than 50 years after his record-setting descent, Walsh became a part of Cameron’s DEEPSEA CHALLENGE team. He is modest about his role.

“Jim said I was a mentor,” Walsh says. “I think that’s a bit optimistic. He’d say how did you do this or how did you do that. Or what kind of problem did you run into with this. So I was just kind of there as an adviser, but not a contemporary adviser. He had a team of 30 technical people that designed and built the thing.”

After Cameron squeezed into the DEEPSEA CHALLENGER for the descent, Walsh gave him one piece of advice.

“Just before he shut the hatch to make the dive, I said, ‘Good luck and have fun,’” he says. “That was my advice. I said have fun.”

Walsh was also able to greet Cameron after the DEEPSEA CHALLENGER successfully made its dive and surfaced.

“When he came back up and opened the hatch, I was there and shook his hand and said, ‘Welcome to the club. There are just two of us,’” Walsh says.

Hopefully, even more explorers will join Walsh and Cameron’s exclusive club.

“The very deepest places of the ocean will mainly be explored by unmanned vehicles, but there will always be room for manned vehicles,” Walsh says. “The unmanned vehicles are going to be doing the heavy lifting in the future, studying the ocean trenches. But there will also be a need for putting humans down there to make direct observations.”

Walsh, like Cameron, remains a passionate advocate for exploring the ocean.

“We’ve only adequately studied 8 percent of the world oceans,” he says. “I’d suggest there’s a lot of work left to do, whether it’s the deepest part of the ocean or anywhere else.”

Unsinkable Don Walsh
Don Walsh served in the Navy, descended to the deepest part of the ocean, taught oceanography at USC, and now works with James Cameron.

Education and Exploration
After retiring from the U.S. Navy in 1975, Walsh became dean of marine programs and a professor of ocean engineering at the University of Southern California in Los Angeles. He believes it is essential to educate the next generation of ocean scientists and engineers.

We need to know the oceans, because they are a fundamental part of our planetary system, how everything works on our planet, Walsh says. Since almost all of us are going to spend our lives on this manned satellite we call Planet Earth, we better know as much about it as we can.


suitable or good enough.


to argue in favor of something.

Challenger Deep

deepest measured point in the ocean (part of the Mariana Trench), about 11,000 meters (36,198 feet), located in the South Pacific Ocean.




arrangement of parts of a whole.


tube or long, circular object.




pre-eminent explorers and scientists collaborating with the National Geographic Society to make groundbreaking discoveries that generate critical scientific information, conservation-related initiatives and compelling stories.


new, advanced, or original.


carrying one or more people.


to advise and influence.


refusing to draw attention to oneself.


person who studies the ocean.


a long, deep depression in the ocean floor.


knowledgeable or complex.


round object.


small submarine used for research and exploration.


the science of using tools and complex machines to make human life easier or more profitable.


up-down direction, or at a right angle to Earth and the horizon.