Originally Posted by crockett

As I posted above it comes down to salvage laws. It's encouraged to salvage the stuff so it's not lost. The people whom salvage it do not own it but are entitled to a salvage reward.

So no legally they can't just take it and sell it on e-bay unless the court awards them title to it. So yes if they take it and sell it or don't report that they have salvaged it. Then it is stealing because there is clear known ownership.

If it was of unknown owner ship then it comes down to finders keepers assuming there are no local laws. For example in the US, any shipwrecks within 3 miles of the cost is claimed ownership by the US govt. However that owner ship is then granted to each state. So depends on what state it's in as to how the law covers it. So just depends on how they treat it over there but overall basic admiralty law covers this.