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TRIESTE at Washington DC Naval Musem
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Going the Last Seven Miles
The Bathyscaph Trieste Story
By CAPT Don Walsh ’54, USN (Ret.)
Source USNA Alumni Pub, Shpmate    May 2000 Edition
USNA/Shipmate Archives

In the late 1930s a Swiss physicist, Professor Auguste Piccard, began development of an "underwater free balloon" for deep ocean exploration. He thought of this concept many years earlier while a first year student at Zurich Polytechnical School. He called his device a "bathyscaph" (from the Greek words "deep" and "ship").

Operating Principle

The operating principle is very simple. The "balloon," called the float, is a thin metal shell filled with aviation gasoline which is lighter than water. Suspended beneath the float is the thick-walled cabin for the crew. The float is fixed with ballast tanks to provide positive buoyancy while on the surface. When vented the ballast tanks fill with seawater creating slightly negative buoyancy submerging the vessel.

Negative buoyancy trim is tested alongside the dock before going to sea. It can be adjusted by adding or removing weights. Once the dive has begun the submersible is slowed or surfaced by releasing weight using solid weights since using compressed air to blow water from tanks is not feasible at great depths. Ballast containers (shot tubs) containing a large quantity of very small steel balls, or "shot," are fitted to the float. The opening at the bottom of the container is surrounded by an electromagnet so when it is energized the shot cannot flow out. With the power off, the shot falls free at a rate controlled by the size of the tub opening. In an emergency, the entire ballast tub can be dropped.

Piccard’s first bathyscaph, FNRS-2, was tested in 1948. It made a manned test to 90 feet and one unmanned dive to 4,600 feet. Both dives were successful but the submersible was not very seaworthy at the surface, therefore, it was taken to the French naval shipyard in Toulon for a complete reconstruction and upgrade. In June 1953, the French Navy launched its first bathyscaph, FNRS-3, which used many of the parts of its predecessor.

After working briefly with the French, Professor Piccard and his son, Jacques, went to Italy and organized a consortium of Swiss and Italian sponsors to build a new bathyscaph, Trieste. Launched on 1 August 1953, it embodied lessons learned from FNRS-2 and their work with FNRS-3. By the end of September 1953, father and son had made a dive to 10,392 feet in the Tyrrhenian Sea near the Island of Ponza.


The twosome also discovered that maintenance and operational costs for the submersible were just too much for them to manage. In 1954, Trieste made one dive and in 1955 it did not operate at all. By 1956 they were looking for someone to rent the submersible on a long-term basis. Among others, the British and American navies were approached, but only the Americans, through the Office of Naval Research (ONR) office in London, showed any positive interest. That year seven sponsored dives occurred in September and October at which time Trieste dove to a new maximum depth of 12,110 feet near Ponza.

In 1957, ONR contracted for a series of dives at Capri. From July to October a total of 26 dives involved marine scientists from a wide variety of disciplines. Each was to evaluate how this platform could improve his practice of science. About this same time the French announced that they were going to build a second, more capable bathyscaph named Archimede (Archimedes).

U.S. Acquisition

At the end of the Capri program, meetings were held in Washington, D.C., to decide whether or not to recommend that the Navy acquire Trieste. A favorable recommendation was made and Trieste was purchased from the Piccards in 1958. The Navy also agreed to fund the purchase of a deeper diving pressure hull for Trieste.

Navy Electronics Laboratory (NEL) in San Diego was the new home of Trieste which was delivered there in September, 1958. Consultants Jacques Piccard and Giuseppe Buono were part of the "package." Piccard was to show the Navy how to operate the submersible and former chief engineer Buono would teach its systems and maintenance.

The newly designated chief scientist for the program, Dr. Andy Rechnitzer, had been busy at NEL putting together the shoreside infrastructure. He was familiar with the submersible’s requirements having participated in the 1957 dives at Capri. Waterfront space was allocated and a building converted for staff and shop functions.

Rechnitzer also arranged to brief the senior submarine commander in the area about the Navy’s new (and first) deep submersible. While the bathyscaph program was sponsored and directed by ONR, with help from the Bureau of Ships, it was important to keep the submarine community informed as well.

ComSubPac’s representative on the West Coast in 1958 was Captain Ralph E. Styles ’33, Commodore of Submarine Flotilla One. This command consisted of some 24 submarines, two tenders, two submarine rescue ships plus the Regulus I missile submarines based up the coast at Point Magu. In addition, an LST was modified to carry a submarine launch system for the new Regulus II strategic missile.


Despite the size of his command, Styles did not have a personnel allowance for staff assistants sufficient to keep up with all his responsibilities. So Commodore Styles and his Chief Staff Officer, Captain Walter L. Small ’38, hatched a plan. They would "invite" a submarine qualified lieutenant (preferably a bachelor) to join the staff on a temporary basis. The officer would come from a submarine as it returned from a six month deployment to the Western Pacific. Since boats returned on average every six weeks this meant each ‘volunteer’ would be on the staff no longer than this time.

I had the "honor" of being the first to be "shanghaied." At the time my boat was Rasher (SSR-269) and we were entering San Diego harbor mid-Summer 1958. I was back at "lines aft" and saw the Commodore’s barge come up alongside forward. As was his habit, he and staff officers would come aboard to greet returning submarines. Wreathed in diesel exhaust and far aft I figured that they would leave me alone. Then from out of the smoke came a Captain. He asked, "I’m Walt Small, are you Don Walsh?" I replied. "Yessir," wondering why I had been chosen for this honor.

A day or two later I got a come-around to call on the Commodore, Chief Staff Officer and the Flotilla Operations Officer, Commander Robert W. Stecher ’43. Clearly these were job interviews. I soon found myself transferred to a small office on the top deck of the tender. My captain had been promised that I would only be gone for six weeks at the most.

That was the theory. After several months I asked Captain Small when I could go back to my boat. Several subs had come back from deployment but there was no relief for me. The answer was a chilling revelation. The Commodore wanted to make my temporary job into the permanent billet of "Flotilla Secretary." Furthermore, ComSubPac, Rear Admiral Elton W. "Joe" Grenfell ’26, said he would give the proposal a strong endorsement and forward it to BuPers. To make things worse, both commands assured BuPers that there was already an officer selected for this billet…me.

You could not ask for better bosses than Styles, Small and Stecher. And the enlisted staff we had was superb. But I was, and am, a sailor. The idea of sailing a desk on board the tender for a couple of years was not appealing at all.

Into this mess stepped Andy Rechnitzer. He came to my office to arrange a Trieste briefing for the Commodore and interested staff members. I heard what Andy had to say and then presented it the boss. He replied, "Yes and invite them to lunch…and you come too."

Andy brought Jacques Piccard with him. At lunch they briefed the Commodore on the immediate Navy plans for the bathyscaph, how it worked, its future importance to the Navy, etc. When Commodore Styles thanked Andy, he asked how the submarine force could help. There was not a bit of delay, "We need two submarine-qualified officers and about five enlisted men to maintain and operate Trieste, and we need them soon." NEL would provide technical support and program guidance but there needed to be a military crew to run the vehicle.

We all went out on deck outside the Commodore’s mess and looked over the side at a Navy harbor tug bringing the barge with Trieste parts alongside the tender. It had not been assembled yet. (This was in the days before the submarine base at Ballast Point so we were moored out in the harbor.) There was a collection of odd bits of metal. To me it looked like an explosion in a boiler factory. Was I really sure this is what I wanted to do? On second thought, that stuff down there was my ticket back to sea. I had little knowledge then of the depth of the ocean or what was involved in being in charge of a bathyscaph. I just knew it was not a desk job.

Commodore Styles agreed that Andy’s request for two officers was reasonable and said he would try to get ComSubPac and BuPers to agree. Meanwhile Captain Small directed me to send a message to all the boats operating in EastPac asking for two officer volunteers with preference for a submarine-qualified lieutenant. Out went the message; the response was curious. Only one volunteer name came back, Lieutenant Dick Davey. With some delicacy I asked if I could put my name on the list. Captain Small reluctantly agreed, so Dick and I became the total volunteer pool.

Once again exercising the same "horseback school of personnel detailing" that got me shanghaied in the first place, the Commodore detailed us in to NEL temporarily with only minimal paperwork. Now the very thing that harpooned me in the first place was working in my favor.

Dick went to NEL in December 1958. Since he was a couple of years my senior, he became Officer-in-Charge of Trieste. Dick was on the scene when the newly assembled Trieste made its first ocean dive in the U.S. Navy.

As Assistant Officer-in-Charge, I would arrive at NEL in January 1959. It was about this time that Dick got sick with a disease that required light duty and a fairly prolonged period of recuperation. He had to step down from the project and I became the Officer-in-Charge. My brief time with Dick showed that he was a good shipmate.

Now I had to find an assistant. Lieutenant Larry Shumaker ’54 had been with me in Rasher. We got along very well; I knew he had the energy and intelligence to do the job. We talked and he was enthusiastic. Captain Small helped me get Larry moved from Rasher to NEL. His commanding officer was not at all happy, but considering the poor turnout of volunteers the first time around and that Larry was a "known quantity," I really pushed hard for this outcome.

The Plan

It was not until I joined NEL as Officer-in-Charge Trieste that I learned what a handful of people had in mind for the bathyscaph. When Andy had briefed the Commodore he had left this one out! The plan was to dive it into the deepest known place in the World Ocean! The location was Challenger Deep in the Mariana Trench some 200 miles from the Naval Station at Apra Harbor, Guam. The depth was about seven miles.

To do this we would install a new cabin (already on order at the Krupp Works in Essen, West Germany), increase the size of the float to get more payload capability and increase the amount of shot ballast we could carry. This work was to be done at NEL and the Navy’s Ship Repair Facility (SRF) in San Diego. It was pretty exciting stuff for a couple of submariners whose sense of ocean depths was basically determined by our boat’s test depth and coastal bathymetry where we might be operating. In other words we didn’t want to run aground submerged or surfaced.

The Project

The first months of 1959 were very busy at NEL. We did a few dives off San Diego in Trieste’s "as delivered" configuration before sending it to the SRF for conversion work. After a dive to more than 4,000 feet in the San Diego Trough I realized this project was going to be pretty exciting.

As delivered the bathyscaph was capable of a maximum depth of 20,000 feet. This limit was imposed by the strength of the sphere (cabin/pressure hull) and the amount of gasoline the float could carry. And 20,000 feet isn’t bad. In fact, 98% of the seafloor is less than this depth. Only 2% is greater. However, Krupp’s new cabin could take us to 50,000 feet, if any place in the ocean were that deep.

Lengthening the size of the float increased our AvGas capacity from 28,000 to 34,000 gallons. Bigger ballast tubs increased shot capacity from 11 to 16 tons. The Krupp Sphere was a thing of beauty. Seven inches thick, it was made in three rings and glued together with epoxy at the joints. The head of BuShips, Rear Admiral Ralph James ’28, came to see Trieste at NEL. He asked how this very smooth sphere was fastened together. I told him it was glued. He fixed me with an admiral’s "evil eye" and said, "Lieutenant Walsh, the Navy does not glue its ships together." Perhaps, but ours was glued.

While the yard work was going on, we were developing an operational plan for our deep dive program, now named "Project Nekton." NEL’s Commanding Officer Captain John Phelps ’34 signed a very strong endorsement and was set to forward it to Washington. However, with so much at stake and not much time to waste, it was agreed that I should hand carry it to Washington.

Once there I was put on sort of a ‘conveyor belt’. The commanders passed me to the captains who in turn passed me to the admirals. And even within the ranks of the flag officers I still moved upward rather

rapidly without any real decisions being rendered. After not too much delay, I found myself in front of Admiral Arleigh Burke ’23. I knew I would get an answer here!

I briefed Chief of Naval Operations and he agreed to the project. However he directed that our intentions not be publicized until we were successful. He did not want a high-visibility flop. I called NEL and gave them the good news.

Test Dives

The modified Trieste was reassembled and performed two test dives off San Diego in mid-September to ensure all the modifications functioned properly. Then we took it apart and loaded it on a commercial cargo ship for shipment to Apra Harbor at Guam. The ship sailed on 5 October with two of our enlisted men along to make sure everything stayed secure. The rest of the team of three military and seven civilians from NEL, came out to Guam before the ship arrived.

The situation at Guam was excellent. We had outstanding support from the Naval Repair Facility and Naval Station. Rear Admiral W.L. Erdman ’24, ComNavMarianas and his staff were solid supporters. From top to bottom the Navy on Guam wanted to help us.

By working from dawn to dusk seven days a week, our little team of military and civilian personnel began a series of increasingly deep test dives from November to December 1959. On 15 November, Andy Rechnitzer and Jacques Piccard set a new world’s depth record with a dive to 18,150 feet.

During the Christmas holiday season Andy, Larry and I checked ourselves out as Trieste pilots making several dives in Apra Harbor. The water was not very deep, but the procedures for making the submersible ready, actual diving manipulation and post-dive requirements are independent of depth.

In January 1960, Jacques and I dove to 23,000 feet. Fifteen days later we finally made the dive into Challenger Deep to a depth of 35,800 feet. We had done what we said we would do. When Andy, Jacques, Larry and I were brought back to Washington to meet President Eisenhower, Admiral Burke was smiling a lot more than when I had last seen him!

Then it was back to Guam for a few more months and Project Nekton II. We intended to return to the Challenger Deep for another dive, however, the Navy reduced Trieste’s depth capability to 20,000 feet. During that summer Shumaker and Rechnitzer dove to that depth in the Nero Deep.

I was relieved as Officer-in-Chief in July 1962. My wish had come true, I did not have to pilot that desk on board the tender!

Trieste was retired in 1963 at the age of ten, after it had returned to NEL from working at the site where Thresher (SSN-598) had been lost. At least two other versions of Trieste, all named "Trieste II", served with the Navy until 1982. With the retirement of Trieste II the world’s last bathyscaph was gone, since Archimede had been retired in the late 1970s. Today Trieste is at the Navy Memorial Museum in Washington, D.C., and Trieste II is at the Navy Undersea Museum in Keyport, Washington.

For more than a third of a century the bathyscaph was the only means to get man into the deepest parts of the oceans. Since those early days, more than 200 manned submersibles were developed worldwide. Few remain in service today, but there are four manned submersibles, two Russian, one French and one Japanese, that can go to 20,000 feet, though there is no submersible in the world that can go beyond this depth. Regrettably, the U.S. no longer has this capability.

Don Walsh’s naval service was in aviation (enlisted), surface and submarine branches. Shore duty was mostly in ocean-related research and development. In addition to deep submergence, he worked in space programs (ocean remote sensing) and in the polar regions at both Poles. President of the Oregon-based consulting practice, International Maritime Inc., he is a 1954 USNA graduate, has a Ph.D. and M.S. in oceanography (Texas A&M) and an M.A. in political science (San Diego State University)

Related Links:

  • TRIESTE via Historic Navy Ships Assoc. (HNSA)
  • USN History Ships   USS THRESHER (SSN-593)   (.mil)
  • USN History Ships   TRIESTE (1958-1963) after 1960   (.mil)
  • USN History   Navy Museum -Washington, DC   (.mil)
  • USN History   Summary of Exhibits at The Navy Museum   (.mil)
  • TRIESTE via Ocean Planet:How Deep   (.gov)
  • The Deep Sea - Journey to the Ocean Floor via
  • United States Submarine Veterans Inc. - Sources, Museums and Misc., Page-2

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