Some would argue that the Soviet submarine K-278 Komsomolets deserves the title for the deepest depth a submarine can achieve at 1,300 meters below sea level. Some of you would say a US Los Angeles-class submarine deserves that feat, at which it can dive about 900 meters. But most have never heard of the Trieste, a US Navy bathyscaphe that reached the bottom of the Sea.

Technically, a bathyscaphe is different from a submarine in many ways. Nevertheless, here’s the story of the historic dive of the Trieste to a world unknown in the 1960s!

The Beginnings of the Trieste

The Trieste was the brainchild of a Swiss scientist, Auguste Piccard, which Acciaierie Terni then built in collaboration with Cantieri Riuniti dell Adriatico in the short-lived Free Territory of Trieste. This is actually where the naval vessel gets its name!

Jacques Piccard, co-designer of the bathyscaphe, and his assistants make final checks aboard her, prior to Trieste's first deep dive in the Marianas Trench. On 15 November 1959 (Wikimedia Commons). Source:
Jacques Piccard, co-designer of the bathyscaphe, and his assistants make final checks aboard her prior to Trieste’s first deep dive in the Marianas Trench. On 15 November 1959 (Wikimedia Commons). Source:

You might have guessed by now that the Trieste wasn’t really made for the US Navy. It was made for the French Navy in 1953 for research purposes. Later on, the French would sell it to the US Navy for $2.2 million at today’s rates.

Why was it bought by the US Navy? During the 1960s, the Navy was involved with a series of tests regarding research for sonar development. This is where Project Nekton comes in, a research project conducted in the Pacific Ocean through the Navy Electronics Laboratory. Its goal was to use data from deep dives to develop Sound Surveillance System (SOSUS) and sonars to track Soviet submarines.

Getting Ready For The Historic Dives

Fitting the Trieste with upgrades to withstand the deepest portions of the world’s ocean was by no means an easy task. Keep in mind that the pressure at the Challenger Deep was at 1.25 metric tons per cm2 – that’s about 100 adult elephants standing on your head on land.

The vessel was fitted with 22,000 gallons of gasoline(which is lighter than water) for buoyancy as air-filled tanks would be crushed by extreme depths,  releasable iron ballast, and fitted with a new pressure sphere in 1958. Because the Trieste was equipped with thick walls to withstand pressures, independent life support systems, a rebreather system, oxygen, and batteries, there was only room for two people to be on board. Additionally, 20,000 pounds of magnetic iron pellets were used as ballast for the vessels. Later, the US Navy would further upgrade the vessel to fit their specifications.  It was still a revolutionary design. Previous vessels were little more than enclosed spheres lowered by a cable from a ship on the surface, the Trieste was capable of freediving and maneuvering while under its own power.

Diving Into The Marianas Trench

Before going into the series of dives into the Marianas Trench, it would undergo test dives at Apra Harbor in 1960 to check for integrity issues that it may have. No problems or issues arose, so the mission was on!

From San Diego, the Trieste was transported to Guam aboard the SS Santa Mariana on October 5, 1959. From Guam, it was tugged by the USS Wandank toward the dive site where it would meet the USS Lewis.

The U.S. Navy bathyscaphe Trieste, just before her record dive to the bottom of the Marianas Trench, 23 January 1960. (Wikimedia Commons). Source:
The US Navy bathyscaphe Trieste, just before her record dive to the bottom of the Marianas Trench, 23 January 1960. (Naval History & Heritage Command, Public domain, via Wikimedia Commons).

Before diving into the Challenger Deep, it had dove into the Nero Deep to research a path for a deep-sea cable route. During these dives, the Trieste encountered several damaged components due to the incredible pressures exerted in deep dives. The crew heard a loud bang when it was ascending from its record-breaking dive of 5,530 meters. It was discovered that the epoxy seals of the vessel had broken, and needed to be repaired. The repairs would go on without a hitch, and the dives that would follow the initial dive in the Nero Deep would break world records, reaching a depth of 7,300 meters.

Finally, the dive into the Challenger Deep was in place.

On Jan. 23, 1960, the first manned vessel with a mission to reach the Challenger Deep was underway. The Trieste, carrying oceanographer Jacques Piccard (Auguste Piccard’s son) and Lieutenant Don Walsh started the descent into the unknown, the first human eyes to see the bottom of the sea.

The descent reportedly took 4 hours and 48 minutes to reach the ocean floor at a rate of 3.29 km/h. Upon passing the 9,000-meter point, the outer Plexiglas windows shattered, shuddering the entire vessel and giving the two-man crew a fright of their lives. At an astonishing 10,916 meters deep, the men had done the impossible, being the first people to have ever laid eyes on the deepest portion of the ocean.

“But once it was underway, the deepest dive in human history was actually a little boring,” said Walsh.

The two men reportedly ate chocolate bars while they observed the marine surroundings, where they observed sole and flounder fish swimming away from the vessel. The ascent back to the top would take 3 hours and 15 minutes to complete.

With that, Piccard and Walsh opened the world’s eyes and a scientific window to the deepest part of the ocean. Walsh would then go on to have a successful career as a captain of US Navy submarines and an oceanographer. Piccard would also spend his life dedicated to studying the underwater realms of the world.

The Trieste was retired in 1966 and its design was the basis of the Trieste II designed to navy specifications,  She currently sits on display at the Navy Museum in the Washington Naval Yard in DC.