I'd put an end any existing laws that ban detecting in the water at the beaches along the treasure coast.
I don't think you can unless the leasees stop paying as they were granted under admiralty law.
The state of Florida and the Federal Government confiscated the treasure from the Atocha and Fisher had to fight it all the way to the supreme court to get what what was his back. However, the do allow other treasure hunters (investors) to participate.
Maybe some day they will allow shallow water hunters to also participate as part of on going the salvage effort.
Unfortunately, this would be difficult to manage because of all the free loaders. Even though I have never met them, but met Art Mcgee, who was considered the father of hard hat treasure hunting, I have the utmost respect for anyone that would take on the state of Forida and the federal government and win.
I know that Art knew of several wrecks, which he would not salvage, since the state would take away too much of the treasure found to be cost effective.
These wrecks may still be out there, and have not been salvaged
