Re: Dear Doctor... How could you do this?
Just because Scotty thought it was ridiculous doesn't mean there were better options available. Since we didn't witness any discussion resulting in the decision to submerge the ship, we're hardly in a position to judge said decision from an in-universe standpoint.
It was the best of Trek, it was the worst of Trek...
"If I lean over, I leave myself open to wedgies, wet willies, or even the dreaded Rear Admiral!"