Just a few comments on water pressure. Dive down 6 feet or so in a swimming pool, then hold your nose and blow out gently into the blocked nose to equalize the pressure -- just do this every 6 feet or so (you'll do this a lot while snorkeling or SCUBA diving) and you can dive down fairly deep before your lungs start to hurt (they will shrink by about half by 33 feet, etc.). The gases inside you are getting compressed so that the pressure inside equals the pressure outside, and with compressed air to refill your lungs you can survive even up to more than 1000 feet... but of course, highly pressurized air isn't the same as sea-level air, and gases start dissolving into your blood (the nitrogen especially). Too much nitrogen will poison you, plus you might end up with dangerous bubbles in your blood (causing decompression sickness) if you are down for too long and come up too fast.

Tie a weight to an inflated balloon and sink it -- it won't break, because the walls are flexible. It'll just shrink as the air is compressed until it looks totally deflated as it goes down. If you kept refilling it with compressed air, you'd be able to keep it inflated; just make sure you vent it as you rise or it will burst then. This is the SCUBA diver approach... when you're resurfacing, you just keep breathing out!

The other approach (e.g. the Trieste) is to avoid raising internal pressure to match external, but instead to counter the external pressure with a structure that can bear the weight. It's possible to go much deeper this way, as you can breathe normal air... but the pressures the craft must bear are incredible.

Next time you're out deep-sea fishing, take one of your specimens in your bare hands.

When you jump into the deep end of a swimming pool, your sinuses start to ache about six feet down. You've got the weight of the water above you pressing on your head, compressing the cavities therein. Your head is being squeezed like a balloon.

Imagine the effect in waters deep enough to stop light.

Most deep sea fish rarely exceed a foot in length; you can hold them in the palms of your hands.

Creatures from the deep sea are squishy.

Most fish are firm — all muscle. But pull them up from deep enough and they feel like Jell-O. Their muscle tissue is more gelatinous — it contains more water than that of upper-ocean fish. They have no swim bladders: swim bladders pop.

The danger in high pressure is not the pressure itself but in pressure differences. Blow up a balloon, tie a weight to it, drop it in the ocean. Before too long the air inside succumbs to the growing weight of the ocean and the balloon breaks. Now drop in a weighted balloon without blowing it up. It sinks without incident and decomposes on the ocean floor. Nothing to collapse.

Submarines are balloons made of metal.


Bathyscaph Trieste —
Turn Greek for a minute.

Bathos is deep
Scaphos is ship.

Deep ship: What an injustice to this vessel.

You cannot go deeper than this machine has gone. It has seen the bottom of the Marianas Trench, some seven miles below the waves. The next time you make a seven mile car ride, imagine that physics has fallen apart in some convenient places and that you're traveling straight down into water. You'll spend several minutes like this.

To be fair, the term "bathyscaph" was coined by vessel creator Auguste Piccard sometime in the early 20th century to describe his idea for a freefloating underwater balloon.

Strange ideas come to fruition sometimes.

The bathyscaph's operating principle is devastatingly simple. Aircraft fuel is lighter than water. Fill a metal tank with fuel; attach ballast containers for positive buoyancy and iron weights for negative buoyancy. Attach a thick-walled iron sphere to the bottom with windows to the outside. Add people to the sphere, release the ballast, let it all sink. When it's time to come back up, ditch the iron. The aircraft fuel brings you to the surface. Like a zeppelin in reverse.

Anything can be simplified. The Trieste carried sixteen tons of iron for negative buoyancy. A bit of perspective. Here are a few more specs.

  • Length of 59.5 feet
  • Diameter of 11.5 feet
  • The original passenger sphere, manufactured by Italy's Industrial and Electrical Company, was comprised of an alloy of nickel, chromium, and molybdenum.
  • The windows in the original sphere were Plexiglas structures six inches thick that tapered inward — sixteen inches wide on the outside, four inches wide on the inside. In the sphere redesigned for Project Nekton (see below) tapered even more sharply, from sixteen to two and a half inches. The sphere itself was a little over seven feet across, with a six-foot interior diameter.
  • The Trieste packed a whopping two horsepower provided by twin electric motors. Maximum speed was one knot.

The name "Trieste" originates from the Adriatic port whose citizens endorsed Piccard's endeavors despite fallings-out with the French over the fate of Piccard's previous creation, the FNRS-3. At the time, the port of Trieste was administered by Yugoslavia, the United States and Great Britain. The FNRS-3 is another story for another day.

Trieste first took to the water in August 1953, months after it was built. After a few short test dives, Piccard and his son Jacques sunk the vessel to 3540 feet. The next year saw a few sparodic dives supplanted by a crippling dearth of funds. Picard could not afford to drive his submarine. Piccard offered his vessel for long-term rental to the British and American Navies, eventually piquing the interest of the US Office of Naval Research based in London. On an ONR-sponsored dive near Ponza the Trieste reached a new depth of 12110 feet.

In 1957 the ONR contracted 26 dives near Capri, manned by scientists specializing in several branches of oceanography. The objective was to verify the machine's use across disciplines and determine whether the US Navy should purchase the Trieste from the Piccards. Subsequent meetings in Washington, DC yielded a positive recommendation, and the US Navy purchased the craft in 1958, piecing together plans to install a stronger dive bubble for operations in deeper water.

Trieste was on its way to the deepest water on Earth — the Marianas Trench1.

In 1958 the Trieste was delivered to the Navy Electronics Laboratory in San Diego. Jacques Piccard included his consultational prowess in the sale of the Trieste — he became the owner's manual, teaching the US Navy how to operate his father's strange craft.

Shortly thereafter the vessel was transported to the Mariana Islands, near the ocean trench that the Challenger II had identified as earth's deepest crevice in 1851: The Challenger Deep. Plans to submerge the ship and observe the sea floor — culminating in a dive to 35800 feet — were dubbed Project Nekton.

The waves were six feet high when Jacques Piccard and Navy Lieutanant Donald Walsh boarded the Trieste from a rubber raft.

Trieste descended three feet per second until Piccard and Walsh put on the brakes at 27000 feet to slow the speed by half. In total, the men sank for nearly five hours. Water temperature at the bottom of the ocean was 37.4°F; the inside of the small cabin was a brisk 45°.

An outer window cracked.

The purpose of Project Nekton was to gather scientific knowledge of sunlight penetration, underwater visibility, transmission of manmade sounds, and marine geological studies of the trench. 2

Piccard and Walsh stayed at the bottom of the ocean for half an hour, observing tiny pink shrimp in the artificial light outside their window.

Anticlimactically, Project Nekton was not the Trieste's final mission. In 1963 she aided in the recovery of the sunk USS Thresher off the coast of Massachussetts about 8400 feet down. She was decommissioned shortly therafter and rests as an exhibit at the Washington Navy Yard.

Today, no functional bathyscaph exists. Man no longer has the technology to descend past 20,000 feet.

1 Today, the deepest part of the ocean is believed to be in the Mindanao Trench off the Philippines at some 40000 feet.
      ... Jesus.

2 UDel College of Marine Studies.


Pope, Steven. "History of the Bathyscaph Trieste: A Thirty-One Year Odyssey."

University of Delaware College of Marine Studies. "To the Depths in Trieste."

CAPT Walsh, Donald '54, USN (Ret.) "Going the Last Seven Miles: The Bathyscaph Trieste Story."

Houghton Mifflin. "Ships of the World: An Historical Encyclopedia."

See also

·         Trieste II

·         Trieste II DSV-1


Edit: DonJaime informs me that James Cameron scraped together the means to visit the Marianas Trench in March 2012.


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