I just came back from a fishing trip to Islamarado. Chartered two trips through a marina there (Capt. Ted Wilson and Capt. Perry Skudera). Caught 4 Tarpon between 75 - 120 pounds and one large barracuda. Islamarado is not too far from Marathon. Here's a link to the marina I chartered out of.

http://www.budnmarys.com/