This one was a tip from Mike at The Fish House, in Key Largo, FL- we asked for “Keys things to do”, he told us to feed the fishes. It is a tourist trap kind of place, but sometimes that is OK- and this is strangely one of those.
I suggest you not go for the “tickle the tarpon’s tonsils” approach shown here (No, fish don’t have tonsils, but you get the idea).
You go through a shed, out onto a pier, and there is an aquatic pen where the tarpon come up from below (the pen is to keep pelicans away, it almost works). A few bucks for a bucket of fish, toss (or hand) them to the tarpon, it is oddly satisfying. Water temperature will have an effect on how active the tarpon are, cool water in winter means they probably won’t jump much, but it is still amusing.
There is an adjacent restaurant, and nearby souvenir/trinket shops off the dirt parking lot, I can’t say much for them, we didn’t try the restaurant. I did have a craving for seafood after feeding the fishes, though.