Re: Only 13,500 feet?!
"In October 1959, after being fitted with a stronger pressure sphere, Trieste was transported to the mid-Pacific to participate in Project ‘Nekton’, in which she conducted a series of very deep dives in the Marianas Trench. On 23 January 1960, she reached a record depth of 35,800 feet in the Challenger Deep, off Guam, the deepest point in any of the World's oceans."
Bathyscaphe Trieste (1958-1963) in 1959-60
You might have heard of it? Anyway, the depth in your article, while an accurate statement, is misleading. The capability was ours just one year prior.
Cheers,
Dan