Legally? Going by whose laws? The legitimate owners of all that wealth are the indigenous inhabitants of the territory it was extracted from by invaders. According to indigenous law, it is definitively NOT legally owned by Spain.
In other cases, Spain has won the rights over salvaged treasure from sunken Spanish ships, as the countries they plundered the gold from weren't countries at the time, but colonies of Spain (for example: Peru).
Sincerely, if this is in International waters, you would think there was a expiry date of shipwrecks and it's finders-keepers after, Oh, I dunno, a few hundred years or so.
I'm British and I don't believe the Rosetta Stone belongs to Britain. However, that's probably a minority view, many people here in Britain are still brainwashed about the glory of empire and all the good it did for the world.
The same could be said about every historical artifact not in display in its native nation. Should we repatriate all artifacts and pieces of art to its original nation?
Well, technically Colombia was then part of the Spanish Empire, and that galleon belongs to the Spanish Crown. I personally don't mind but knowing how low gold is in the spanish central bank, probably the spanish gov will make some kind of move to get back its "historical heritage"...
Empire which was revoked due to being an illegitimate and genocidal regime. Your argument suggests they should be allowed to re-steal now what they would have stolen back then.
No, I'm not saying that they should be allowed to re-steal. I said that I don't care about a shipwreck, but the spanish government has been known to claim this kind of finds in the past because technically that is a Spanish ship and legal precedents exist.
Also, all the global empires have been built on the same coercive foundation, and that doesn't make them "regimes".
The reduction of the North American Indian population from an estimated 12 million in 1500 to barely 237,000 in 1900 represents a"vast genocide", the most sustained on record.