Anything that sunk in the last hundred years is still "owned" by someone. If one approached the insurance company involved, or the cruise
company and submitted a bid for salvage, (you and a hundred other salvage companies), you would probably get paid a share of the salvage costs if you won the bid.
These days treasure hunters are having a tough time of it. Anything that sunk in more than a hundred years, is claimed by a dozen governments as an "antiquity", or historical relic. Even the finder the the Atocha has had to ward off dozens of lawsuites and claims, from everyone from the decendants of the former shipmates, to the decendants of the Mayans, who claim the gold originally belonged to them, to the Spanish, Bahamas
, and U.S. government
, who all claim jurisdiction, primary ownership
, and taxes
owed, (which add up collectively to more than 100% of the estimated value).
Recently the son of an elderly eccentric wealthy woman found a stash of cash under her matteress after she died,...It was seized by the police because he could not prove it was lawfully earned, and that she had paid all the taxes
Sadly the days of "finders keepers" is long gone.
If by some chance you did find gold under the rainbow, you would have to not only pay the "windfall" tax, you would also have to fight a claim by the lepracons association.