All submarines have a rated "Crush Depth", the depth at which the hull will succumb to external sea pressure.
While the actual depths for each class are classified, several submarines were lost during the Cold War to implosion events after major casualties. The most noted for the United States was the USS Thresher (SSN-593) which was lost during sea trials after she suffered a major flooding casualty. It was estimated she made it to within 100' of the surface before sinking to her crush depth and the bottom of the ocean.
a Submarine?
Commonly known as a Submarine
That is the correct spelling for "submarine" (underwater, or underwater vehicle).
As far as I can remember, there was never an underwater Russian submarine in Diamonds Are Forever. The underwater Russian/Soviet submarine was destroyed after the USA Titan II missile base was blown up, and before the Chinese missile base was blown up. Your memory is not very good.
As regards torpedoes or missiles, yes, the submarine has weapons that can be launched underwater.
The pressure of the water that deep would crush a person.
A valley that is underwater.
A submarine
A vessel that travels underwater is termed a submarine.
Submarine
Submarine
A submarine.