Can a submarine sink if it's already submerged? Or at the bottom? Do we need a new word? Or do we need to say "losing air," "lost air," or "lost all air" instead?

(First of all, precision and "literal" are not the same, [hurumph emoticon] )

But to the point: my guess, which is subject to amendment, would be that as long she's buoyant, she's afloat; that is, there's no substantial difference between a vessel on the surface or one below so long as each is buoyant. Do you say a ship is sunk when you can't see the red of her keel? If she's resting on the bottom, she can't go down, so she can't sink. She floods or is crushed. In my mind the question is, what's the status of a submarine resting on the ocean floor? Or not what by why.