
A decade before the late 1960’s Apollo Moon Missions, two aquanauts, traveled to the last unexplored place on Earth, the deepest point under all the Earth’s oceans. On 23 January 1960, Jacques Piccard and Don Walsh, in the bathyscaphe Trieste, descended down to the bottom of Challenger Deep in the Mariana Trench, 7 miles, (11 km) beneath the water surface.
The lowest point on our planet is deep underwater, in the western Pacific Ocean near the island of Guam. It’s here where converging geological plates crash together, forcing one plate down beneath the other, forming the formidable Mariana Trench. The deepest portion, at nearly 11,000 meters was discovered in 1951 by the British survey ship Challenger, hence the name “Challenger Deep.”
The distance between the surface and the trench bottom is greater than the height of Mount Everest.
The Trieste ‘bathyscaphe’ was named after the Italian city of its birth. A bathyscaphe (deep boat) is a type of mini-sub with a ‘bathysphere’ attached to the bottom for piloting and observation. Auguste Piccard, a visionary Swiss inventor and aeronaut designed the Italian-built Trieste, a precursor to today’s modern submersibles. Piccard was already famous for setting the record for the highest altitude balloon flight ever thirty years earlier in 1932.
Trieste’s two-man crew would be working inside a 6.5 foot (2 meter) wide pressure sphere lodged on the underside of the submersible. To withstand the intense pressure at the bottom of Challenger Deep [8 tons per square inch or 15,750 psi], the bathysphere’s walls were 5 inches (8 cm) thick. To see outside into the dark depths, the crew would rely on a single window made of a solid cone of Plexiglas.

The rest of the nearly 60-foot (18-meter) long Trieste was primarily a 50 ft. tank. It was filled with 33,350 gallons (126,240 liters) of gasoline for buoyancy. Plus nine tons of iron pellets as ballast to weigh it down. (Why gasoline? Because it is more buoyant than water and resistant to compression.) The Trieste also had the advantage of being controlled by the pilot inside and didn’t need to be tethered to any surface ship. Piccard developed an ingenious method to control the buoyancy, using both the gasoline and iron pellets.
Why partake on such a dangerous mission?
During the Cold War, the U.S. Navy realized the ocean depths could be exploited for military advantages against the Soviets. The Office of Naval Research purchased the Trieste in 1958 and hired Auguste’s son, Jacques, as consultant. The dive was not just about setting a new record, the Navy wanted to prove the feasibility of human exploration at such extreme depths, Project Nekton.
Piccard’s radical design would be put to the test in January 1960 at the deepest place on Earth, with none other than his 38-year-old son Jacques as one of the 2 crew. So a U.S. Navy ship, the USS Wandank, carried the small sub to the South Pacific Ocean for its historic dive into the Mariana Trench. 31-year-old oceanographer Don Walsh, a U.S. Navy Lieutenant, would be the other “aquanaut.”
Floating over the undersea trench after launch, the 2 men waved one last time to the crew of the mother ship. They then climbed down through a tube in the Trieste ballast tank into the bathysphere underneath. It took 4 hours and 48 minutes to drop to the very bottom of the Challenger Deep at a rate of about a yard (0.9 m) a second. One can only imagine the creeping fear and tension the two men experienced trapped inside. They descended slowly and silently into the pitch-black darkness, the bathysphere getting progressively colder and colder with each minute.
The Trieste’s hull could buckle at any moment from the extreme pressure, or it might violently explode without warning.

As if to highlight the peril, after passing 27,000 feet (9,000 meters) the outer window pane cracked, violently shaking the entire sphere! Were they about to die? Should they abort? But since no leaks or pressure drop occurred, the brave men decided to continue their decent. Throughout much of the trip, they lost contact with their mother ship on the surface. Nevertheless, Piccard and Walsh successfully reached the flat bottom of the Mariana Trench at a depth of 7 miles.
The floor of Challenger Deep was a fine, snuff-colored, oozy silt made of microscopic algae known as diatoms. The explorers were shocked to see jellyfish, shrimp-like creatures, and a couple of small white flatfish, proving that some life could withstand the extreme depths. Unfortunately, they carried no external camera and one of the external lights had imploded from the extreme pressures. Skeptics at the time criticized Piccard’s observations, claiming life was impossible at such depths and they were hallucinating from the pressure.
Due to the cracked window, two men decided to spend just 20 minutes on the Mariana Trench floor.
Eating chocolate bars for energy, the pair shivered in the cold. The bathysphere temperature was only 45 F (7 Celsius). The water temperature outside was 39 F/4C. They finally managed to speak with their mother ship using a sonar-hydrophone. Traveling at a speed of nearly a mile per second, it still took 14 seconds for a message to travel from the Trieste to the surface and back again.
Piccard slowly and carefully unloaded the iron pellet ballast and the floor of the Mariana Trench disappeared beneath them. The Trieste began to slowly float back to the surface. The ascent was much quicker than the dive, taking only three hours and fifteen minutes. If you consider that faster, when you are freezing inside a cracked, cramped, and cold dark sphere.
At the surface came cheers and champagne from the U.S. Navy crew. As word spread, both men were celebrated internationally as two of the world’s great modern explorers. For a time, the Piccard family, father and son, held the record for both the highest altitude balloon and the deepest ocean dive.
The historic dive ushered in a golden age of underwater exploration. Men like Jacques Cousteau and Robert Ballard led the way in which submersibles, both manned and unmanned, would make amazing discoveries in oceanography, marine biology and exploration. Ballard went onto discover the wreck to the RMS Titanic in the North Atlantic using submersibles in 1985. In fact, Robert Ballard made his first submarine dive in Jacques Piccard’s next submersible, the Ben Franklin in 1969.
The Trieste was retired by the U.S. Navy in 1963. You can view the original today on exhibit at the U.S. Navy Museum in Washington DC. So costly and risky was the descent into the Mariana Trench it was not attempted it again for another 52 years. It’s been repeated only once, in 2012. This time done solo by Canadian explorer and filmmaker James Cameron (of Titanic and Avatar movie fame). He did it in the torpedo-shaped, DeepSea Challenger. Don Walsh was a part of his research team. And this time, Cameron was sure to take copious videos, recording the sea life. It was more than enough for an award winning documentary James Cameron’s Deepsea Challenge (2014).























