CHALLENGER DEEP, MARIANA TRENCH, SOUTHEAST OF GUAM (WHTM) — The first dive to the deepest part of Earth’s oceans had its start with a record-breaking ascent into Earth’s atmosphere.
On May 27, 1931, Swiss physicist and inventor Auguste Antoine Piccard (1884-1962) climbed into a pressurized gondola he designed, and with fellow scientist Paul Kipfer took off from Augsburg, Germany, suspended from a hydrogen balloon (which Piccard also designed.) They became the first human beings to enter the stratosphere, reaching a height of 15,781 meters or, if you will, 9.8 miles or, if you will, 51,775 feet. That’s 22,743 feet higher than the summit of Mount Everest.
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The trip wasn’t just about setting an altitude record, though. Piccard and Kipfer gathered information about conditions in the upper atmosphere, as well as cosmic rays. Piccard’s pressurized gondola proved it was possible (with proper engineering) for human beings to survive at great heights. (Think about him the next time you’re breathing comfortably in an airliner at 35,000 feet.)
Professor Piccard is now in Brussels, July 1, 1932, where he is making preparations to beat his own record for 10 mile ascent into the stratosphere in a special balloon. (AP Photo) 
Prof. Auguste Piccard, Belgian Physicist and his aide, Charles Kipfer, were reported, May 28, to have reached a height of 52,500 feet over the Tyrolean Alps. This is but 300 feet less than ten miles and establishes a new altitude record. The flight was made in a specially constructed metal ball compartment attached to a balloon. Prof. Piccard, left, and Kipfer work on the balloon, a short time before they made their record ascent, May 28, 1931. (AP Photo) 
The Swiss Professo Auguste Piccard will arrive in Augsburg at the end of the week to the possession of the balloon, built for him shown in Augsburg in which he will ascend to 16,000 meters (53,000 feet), an altitude never reached before. O.P.S. the ball, which will be adjusted in the place of a basket and in which Prof. Piccard will ascend. (AP Photo) 
Professor Auguste Piccard takes off in his balloon at Zurich, August 18, 1932. (AP Photo) 
Professor Auguste Piccard with his wife and children photographed beside the metal cylinder in which he made the ascent 10 miles from Augsberg on May 28, 1931. (AP Photo)
Piccard’s balloon design was just as important. He knew the hydrogen gas would expand as atmospheric pressure decreased. So, he made the balloon’s gas envelope flight larger than the amount of gas needed to get his gondola off the ground. The hydrogen could then expand without straining the bag. The same principle is used for balloons to this day-and Piccard’s understanding of the effects of pressure would prove essential when he turned his attention to exploring the sea.
Human beings had been exploring and working underwater for centuries, using various kinds of diving bells. But diving bells tend to sit (or dangle) in one place. Piccard wanted something that could move, and dive deep. In 1937 he designed the bathyscaphe, a sort of underwater blimp or dirigible.
Like an airship, the passenger gondola hangs under a floatation envelope. Unlike the gondola of Piccard’s balloon, however, the sphere on a bathyscaphe must resist pressure from the outside and has to be stronger. Much stronger. (I’ll toss out some numbers later on.)
Those pressures also meant Piccard couldn’t use any sort of gas for buoyancy. Ocean pressures are measured in “atmospheres.” Every 10 meters (or 33 feet) the pressure increases by one atmosphere-and gas compresses, becoming less buoyant. Instead of an envelope that would expand and contract with the lifting material, he needed a lifting material that wouldn’t expand and contract, to go in an envelope that wouldn’t need to expand and contract. (And it would help if the lifting material was cheap and readily available.)
Piccard’s solution-use liquid instead of gas for buoyancy. Liquids don’t compress as readily under pressure as gases, and some liquids are lighter than water. So Piccard filled the buoyancy chambers of his bathyscaphe with gasoline, a full 30% lighter than water. The bathyscaphe would float until water filled two ballast tanks, then start sinking slowly. To return to the surface, the operators would release iron ballast.
Piccard had to wait until after World War 2 to build his first Bathyscaphe, the FNRS-2. After a series of successful test dives, it was purchased by the French navy, extensively modified, and renamed FNRS-3. Auguste Piccard, now aided by his son Jacques, took what he had learned to design and build a third bathyscaphe, the Trieste, named after the city where it was constructed. It was launched in August of 1953, and over the next few years conducted a series of dives in the Mediterranean Sea.
The Bathyscaphe rebuilt by the French Navy in which Belgian Professor Auguste Piccard is to carry out sea bed research now looks like a submarine. It is being weighed before making its first experiment dive at Toulon, Southern France on June 3, 1953. (AP Photo) 
The French navy bathyscaph FNRS3, with which the French hope to beat the world deep-sea diving record set by professor Auguste Piccard January 27, dived, unmanned, to a depth of 13,000-feet in a test near Dakar, French West Africa. The bathyscaph takes on petrol at Dakar on Jan. 27, 1954 ready for the test dive. (AP Photo) 
The French navy bathyscaph FNRS3, with which the French hope to beat the world deep-sea diving record set by professor Auguste Piccard January 27, dived, unmanned, to a depth of 13,000-feet in a test near Dakar, French West Africa. The bathyscaph shortly before leaving Dakar on Jan. 27, 1954 to make the test dive, aboard is an engineer of the escort ship Elie-Monnier. (AP Photo) 
Two French naval officers, Lieut. Comdr. Georges Houot, and engineer officer Pierre Willm, set up a new deep sea diving record February 15, when they descended to a depth of 13,287 feet, about 2½ miles, at a spot 120 miles off the French West African Port of Dakar. In the bathyscaph FNRS-3, they took 3½ hours to reach the Atlantic sea bed, where they had lunch. They reported feeling no discomfort. Their dive beat the previous record held by Professor Auguste Piccard, who made a descent in another bathyscaph to a depth of 10,335 feet in the Mediterranean. The Bathyscaph is seen on left in this serial picture, with the dinghy alongside on Feb. 15, 1954. On left is the parent vessel, Beautemps Beaupre. (AP Photo) 
Swiss-Belgian explorer Auguste Piccard is seated on the bathysphere in which he hopes to reach new ocean depths just before a test dive in the stubby submarine device at Castellammare near Naples, Italy on August 18, 1953. His son Jacques is waving his hand trying to chase the photographer away. Piccard went down 65½ feet in the test, but he hopes to reach a depth of 12,790 feet. (AP Photo/Ugo Sarto)
The U.S. Navy purchased the Trieste in 1958. They planned to use it for Project Nekton, a series of research dives near Guam, and especially the Marianas Trench. The Navy modified Trieste for the project, equipping it with a new, stronger pressure sphere, manufactured by the Krupp company in Germany.
On October 5, 1959, Trieste left San Diego for Guam aboard a freighter. Guam had a major naval facility and was located only about two hundred miles from the Challenger Deep.
Over the next several months, Trieste performed eight dives, going progressively deeper. The first two dives were in Apra Harbor to test the bathyscaphe and its equipment. Dive three took her to a depth of 4,900 feet.
Dive four was the first really deep dive, to a part of the Marianas Trench known as the Nero Deep. Trieste reached a depth of 18,150 feet. As the ship returned to the surface, though, there was a loud bang at about 30 feet deep. Some epoxy seals had broken on the sphere, and some water leaked in. Trieste had to be hauled out of the water for resealing and adding reinforcing bands.
Dive five was another harbor test of the seals and some newly installed equipment. This was followed by a checkout dive to 5700 feet.
The seventh dive took Trieste to the Nero Deep of the Marianas Trench, a new record depth of 24,000 feet, and a couple of noisy, disconcerting explosions at around 20,000 feet. Somebody had forgotten to remove a portable navigation light, and a new pipe stanchion collapsed because no one had drilled holes in it to allow pressure to equalize. But there was no damage to Trieste herself, and it was time for the deepest dive of the series.
The bathyscaphe Trieste, displaying the Italian and Swiss flags, is shown after its record plunge of 3,150 meters, 10,330 feet, to the bottom of the Thyrrhenian Sea off the island of Ponza, about 50 miles west of Naples, Sept. 30, 1953. Jacques Piccard holds onto his father, physicist Auguste Piccard, holding on to the turret, before descending into a rowing boat. (AP Photo) 
Swiss-born scientist Professor Auguste Piccard and his son Jacques, plunged their strange-shaped bathyscafe Trieste to a depth of 3,150 meters (10,330 feet), touching the bottom of the Thyrrhenian Sea off the island of Ponza, about 50 miles West of Naples September 30. Two Italian naval corvettes were standing by, the Fenice with news and radio men aboard and the Tenace which towed the Trieste into position. Prof. Piccard’s bathyscaphe, Trieste lying between the two Italian corvettes, Tenace (left) and Fenice (right), off the island of Ponza (background), before the record dive on Sept. 30, 1953. (AP Photo) 
Jacques Piccard, son of Professor Auguste Piccard, poses at a news conference in Washington, Jan. 8, 1958, holding a model of the Piccard bathyscaphe Trieste. Jacques Piccard piloted the bathyscaphe when U.S. Navy scientists made a series of 26 dives in it off the Italian coast, near Naples, last summer and fall. (AP Photo/William J. Smith) 
Navy Lt. Don Walsh, above, of San Diego shown Jan. 23, 1960 and scientist Jacques Piccard were aboard the Navy’s bathyscaph Trieste when it set a new world diving record of 37,800 feet, January 23, the Navy announced. The craft went to the bottom of the Marianas Trench in the Pacific. (AP Photo) 
Exterior of Bathyscape (Trieste) June 1963. (AP Photo) 
Interior of Bathyscape (Trieste) June 1963. (AP Photo) 
Jacques Piccard, Guiseppe Buono, and Ernest Vigil inspecting the Bathyscaphe Trieste after the first dive off the coast of Guam. 1959-11-10 (National Archives) 
Bathyscaph Trieste entering the water. April, 1959. (National Archives) 
Showing overall view of fueling operations at NSD Guam. LT Larry Shumacker on deck of Bathyscaph Trieste checking the depth of gas in the tanks. November 1959. (National Archives) 
Left to Right: Lieutenant Larry Shumaker, Assistant Officer in Charge; Lieutenant Donald Walsh, Officer in Charge; Dr. Andreas B. Rechnitzer, Scientist in Charge; Jacques Piccard, Co-Designer and Technical Advisor of Bathyscaphe Trieste. (National Archives) 
The Bathyscaph Trieste is ready to be lifted off the YG-193 to the SS Santa Maria for shipment to Guam. October, 1959. (National Archives) 
Interior of Trieste, circa 1963 (National Archives) 
Trieste at Navy Museum, Washington D.C. (NHHC) 
Observation Sphere of Trieste, Navy Museum, Washington D.C. (NHHC) 
Side View of Trieste observation sphere, Navy Museum, Washington D.C. (NHHC)
On January 23, 1960, Trieste slipped under the waves, beginning the five-hour-long trip to the Challenger Deep, located on the southern end of the Marianas Trench. On board were Jacques Piccard and Lt. Don Walsh. They took readings of temperature pressure, and descent speed, checked the ship’s systems, and peered out the tiny plexiglass window looking for signs of life, of which they saw very little besides phosphorescent plankton. They were able to communicate with surface vessels using a sonar telephone.
Then at 32,500 feet, something broke.
The pressure sphere shook and the men heard a cracking noise. But there was no obvious damage or leakage and the descent was continuing normally, so they pressed on.
And when they reached a depth of 35,797 feet, the Trieste quietly settled on the bottom of the Challenger Deep. One of the very first things they saw in their floodlight-a foot-long fish, swimming slowly away from the mysterious bright-eyed intruder. The question of whether life could survive at such crushing depths was answered. (“Crushing” is the right term; at 35,797 feet, water was pushing on the sphere at 15,519 pounds-over seven tons-per square inch.)
Walsh and Piccard spent twenty minutes on the bottom, taking measurements and peering out their viewport. At one point they swung their searchlight around and found out what had caused the shaking and noise. One of the plexiglass panels on their entrance tunnel had cracked. This wasn’t really a danger to the Trieste, but if it shattered on the way up, it would have to be replaced before they could clear the passageway and climb out of the sphere.
Fortunately, nothing else went wrong with the panel during the three-hour trip back to the surface-but they pumped out the passageway very slowly and carefully when they got to the surface.
The Challenger Deep would not be visited by a manned submersible for another 52 years. Finally, in March 2012, filmmaker and inventor James Cameron piloted a one-man submersible, the Deepsea Challenger, to the bottom, reaching 35,787 feet, and was able to spend several hours collecting samples and shooting video. (Don Walsh was an advisor on the project. )
Then on April 28, 2019, the DSV Limiting Factor reached a depth of 35,853 feet, beating Trieste’s record by 56 feet. It also became the first sub to make more than one dive-four in all between April 28 and May 5.
In 2020 the Chinese submarine Fendouzhe (“Striver”) completed 13 dives in the Marianas trench.
As for Trieste herself, you can see her at the Naval Museum in Washington, D.C. In 2020, Don Walsh was interviewed at the museum. You can see the interview here.
For footage of initial tests of the Trieste, click here.
For footage of one of Auguste Piccard’s balloon launches, click here.
So, Trieste’s record has been broken, after fifty-nine years, and more expeditions to the deepest point in the ocean may be expected. But Jacques Piccard, Don Walsh, and Trieste will forever be the first.
