Onboard Makai we carry a garrett seahunter II. We hit almost every beach and found silver
bolivar coins from the 60's (when they were worth something) to coins by the ton along with one 3 diamond ring.
The best place was the beach in Phillipsberg, StMartin. We only hit about 2% of the primary beach area. The picture is 1 hour worth of hunting. We have a swag bag of everything we found, except for giving aaway some things to the kids on the beach. They amazed.
You probably won't get rich, but it is fun and profitable as well as great excerize.