If, say, the Bismarck hadn't flipped over when it sank, the main battery turrets would still be in their slots, and still (if you raised the thing), theoritically operable. But it flipped over on the way down, the turrets fell out because they were held in by gravity, and then it flipped rightside up once it had completely filled with water but before it hit the bottom.
Or, for the torn into bits, there's what's left of the Imperial Japanese Navy's Yamato. The turrets fell out of it too, but between a hundred feet of the bow and a hundred feet of the stern, it's bits of scrap scattered everywhere. The main battery turrets, though, are still theoritically operable. They'd need to be raised, have the barrels cleaned, placed in a hull or emplacement that could handle the recoil, given power to traverse and elevate, but they could in theory still work.
