After planning a trip to Florida I really wanted to try and dive the Blue Heron Bridge. We entered the water at high slack tide, which was 8am. We just pootled around without too much idea what we were doing but found heaps of critters. I would definitely recommend checking out this link for information about that dive if you're interested.
We also went up to the Crystal River area to swim with manatees and dive the Rainbow River. All in all I was very impressed with the diving in Florida. Shame I didn't have my camera when I saw the Great Hammerhead off Key West!