If you're talking about sunken ships and gold leases in Florida, most likely you're talking about the 1715 Plate Fleet off the Treasure Coast. These ships were carrying Incan gold by way of Havana, some of it still in the Incan form, and others remelted into bullion, jewelry, etc.
There are a couple of rumored/legend Incan repositories being actively searched for in the Andes, but the original placer was mined off the backs of slaves and servants, flake by flake, from Andean rivers. As I understand, as is usually the case elsewhere, the easy stuff has been mined, and all that's left is low-grade placer. In a land of little government regulation and lack of enforcement, the locations where the gold is present in greater quantities is being torn apart, rain forest burned down, etc., and it looks like a moonscape.
My memory is a little fuzzy with the details of Mayan gold, but if I remember correctly, there wasn't a comparable amount of it available for plunder. Montezuma was pretty crafty, and when he realized that the Spanish were probably going to be successful in stealing it, he loaded much of it into a mule train that was taken north into the present-day U.S. (It's theorized that the gold "mine" Brigham Young used to smelt the Mormon gold was actually a cave where Montezuma's gold was hidden.) Both the Incas and Mayans also dumped it into ceremonial sinkholes.
There is some placer gold in Mexico, but again, the deposits may have been locally good but regionally spotty. It's also possible that some was stolen from the Incas.
