Had a great time at the History of Diving Museum just south of Key Largo in Islamorada, Florida. I think this place is just a year old. It was created by a husband and wife who were both physicians, and both avid collectors of rare diving artifacts.

The museum covers diving history all the way back to the ancient Greeks, specializing in artifacts of very early attempts at diving (including an historic diving bell) up to the strange metal atmosphere pressurized suits created for deep recovery diving. It has a very extensive collection of diving helments, including a really fun and bizarre collection of homemade diving helmets.

Some fun interactive stuff for kids.

Not too big, but lots of fun. If you're lucky and the manager Carrie is working that day, you will also be able to get a serious history lesson in the famous Spanish galleon wrecks along the coast of the keys.