
A decade before the 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 ocean’s surface and the bottom of the Mariana Trench is greater than the height of Mount Everest (at 8,850 meters).
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 Trieste, a precursor to today’s modern submersibles. Piccard was already famous for setting the record for the highest altitude balloon flight ever in 1932.
Trieste’s two-man crew would be working inside a 6.5 foot (2 meter) wide pressure sphere on the underside of the submersible. To withstand the intense pressure at the bottom of Challenger Deep [8 tons per square inch!], the bathysphere’s walls were 5 inches (8 cm) thick. To see outside, 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 filled with 33,350 gallons (126,240 liters) of gasoline for buoyancy, along with nine tons of iron pellets as ballast to weigh it down. (Gasoline is more buoyant than water and resistant to compression.) The Trieste also had the advantage of being controlled by the pilot 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 pellets.
Why partake on such a dangerous mission?
During the Cold War, the US 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.
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 the US Navy carried the small sub to the Pacific for its historic dive into the Mariana Trench. 31-year-old oceanographer Don Walsh, a US Navy Lieutenant, would be the other “aquanaut.”
Floating over the trench, the 2 men waved to the crew of the mother ship, then climbed down through the Trieste, 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 2 men experienced as they descended slowly and silently into the pitch-black darkness, the bathysphere getting progressively colder and colder.
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! 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 bottom of the 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.
Due to the cracked window, two men spent just 20 minutes on the trench floor.
Eating chocolate bars for energy, they shivered in the cold. The bathysphere temperature was only 45 F (7 Celsius). They finally managed to speak with their mother ship using a sonar-hydrophone. Travelling 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.
Piccard slowly unloaded the iron pellet ballast and the Trieste began to 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, cold, dark sphere.
At the surface came cheers and champagne. Both men were celebrated as two of the world’s great 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, with men like Jacques Cousteau leading the way, in which submersibles would make amazing discoveries in oceanography.
The Trieste was retired in 1963 and 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 solo done by Canadian explorer and filmmaker James Cameron (of Titanic and Avatar movie fame) in the torpedo-shaped, DeepSea Challenger. And this time, Cameron was sure to take copious videos, enough for an award winning documentary of the same name.
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