What depth have we managed to reach into the sea by submarine or other means?

[Cliff]

while i wont dispute any of the excellent answers so far provided (or give them thumbs down, which i expect to recieve a few of), one thing that muct be considered on questions like this:
CLASSIFIED.

if the US navy has submarines capable of going 25,000 feet down, most of the world will not know that until something new and even more classified is going 30,000 feet down.....


"other means"
i assume you mean methods that actually tell us something..... cause i could go out and drop a rock into the deepest place in the world and reach the farthest spot possible, but it wouldnt tell me anything at all.
manned vessels will always have limits as they must provide protection for the crew. but unmanned has no limits beyond what the equipment itself can handle, new technology comes out daily.