Heroes: Aquaman of the Abyss

The only man to reach the bottom of the sea

In January 1960, oceanographers Jacques Piccard and Don Walsh climbed into a Swiss-made bathyscaphe - or deep-diving boat - and submerged to a record-breaking depth of 35,761 feet. That's 6,732 feet deeper than Mt Everest is high. Piccard died last year, meaning Walsh is now the only living man ever to have touched the deepest part of any ocean on Earth - the Challenger Deep in the Marianas Trench.

"We had been working in Guam for around six or seven months before we made the deepest dive because Guam was a major naval base and could support our logistics. It's also only 200 miles from the Marianas Trench, the deepest part of ocean. We did several dives to prove out the bathyscaphe and test the changes we made to it.

By the end of 1959 we had gone to a depth of around 18,000 feet, which was already a new world record - the French had taken theirs to 12,500 feet in 1954. Then, in January 1960 we made a dive to 24,000 feet and two weeks later we went to the ultimate depth.

To be honest, the only difference really is the length of the trip. All the manipulations are the same whether you're going down a few hundred feet or tens of thousands. It's like flying - you pre-flight the plane and there are procedures you follow. And all of these are the same whether you're going five miles or 5,000 miles.

There is greater pressure at a greater depth, and the machinery is running longer. But basically, this wasn't rocket science so I wasn't nervous. It was the same drill for me - just further out to sea and we knew we'd be gone for a bit longer.

I don't recall anyone else being worried for me. I don't think my parents really knew what I was doing. I wasn't married at the time, although I had a girlfriend. She covered up her uncertainties by going skiing. We later got married so she had to pay her dues - she's downstairs right now after 47 years. She's a 'keeper', as they say!

The whole dive took nine hours - four hours down, half an hour on the bottom, and the rest of the time coming back up. Nine hours may seem like a long time to be submerged but I made a dive on the Bismarck wreck in 2003 and that lasted 14 hours - and that was only to 15,500 feet. Danger is in the eye of the beholder.

At one point on the way down, one of the outer window panes cracked. Of course we didn't have glass - it was made of acrylic plastic or Perspex - and luckily the thing that cracked was actually not a pressure boundary window. It was just a window that allowed us to look outside, so there was no danger of being flooded. we were at 20,000 feet when it happened. If it had been a failure of a pressure boundary window we would have died instantly.

Normally when you make a landing with a bathyscaphe you stir up the bottom sediment - it's like dropping a ball in the dirt. The cloud floats up and then the current carries it away, and by the time you've tidied up after landing, checked the lights, etc., you can turn attention to looking out the window. But there was no current at 35,000 feet. It was like being in bowl of milk - just clouds of white sediment, so we couldn't see anything.

We were about a mile deeper than Everest is high. It was late January and the outside temperature was about 34 degrees Fahrenheit (about 1 degree C). Yes, it was cold, but with the equipment running, our warm clothing, and body heat, we didn't get too cold.

Our primitive bathyscaphe was like the Wright Brothers' first aeroplane. The pioneers have to start somewhere - and we wrote the book on how to do this. Today we still see our fingerprints on undersea operations - and not just on manned vehicles but unmanned as well. There is a reason man hasn't been down again. The deepest manned submersibles today are all clustered around 20,000 feet depth - that accounts for around two thirds of the maximum depth fo the ocean. And for that you don't need an expensive submersible that can reach 36,000 feet.

But it's like someone saying you can climb all the world's mountains except the top 3% (which would include Everest). It would be nice if they sent man to the bottom of the Marianas Trench again. When we finsihed our deep diving programme at Guam we figured it would only be a matter of time.

Studying these trenches is important to understanding the processes that occur on our planet - like plate tectonics. For me it's about doing field work to gain knowlege for mankind. And that's what we did - it wasn't just to set a record.

Some people say we just went down and didn't see anything - that it wasn't very useful. But the Wright Brothers only flew 200 feet."

See the animation of the Marianas Trench in our video section

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