RC owns Coco Cay, purchasing it from the individual owner who they originally leased it from. The previous owner had bought it from another individual owner years ago.
It's still the Bahamas and subject to Bahamas laws though.
Here's an interesting history of the island, including its role as a failed shrimp farm and as a drug cartel staging area.
https://www.cruisetricks.de/how-little-stirrup-cay-became-royal-caribbeans-private-island-coco-cay/