Fair enough RE: Hunley, but I think that's the exception to the rule. It's "small enough" that it can be placed inside a museum somewhere. Full battlecruisers, on the other hand, carriers, battleships, cannot be displayed so easily.
I can think of only one other example, and that was a wooden sailing ship preserved in cold water fjords off of Finland or Sweden or something.
WW2 wrecks? Most folks treat them with a reverence (well deserved) that prohibits exploitation of the wreck.