This was amazing, the snorkeling around fort Jefferson is great. The forts was built by the union before the civil war and it still stands. it is now part of the Dry Tortuga national park on Garden Key.
Corals and reef fish big and small are now abundant around the submerged portions of the brick walls of the fort. There a lot of really big fish here. We saw tangs, Stingrays, Barracuda, parrot fish, and wrasse. The coral growth on the walls was great. On the walls there a smaller critters like green crabs and hermit crabs. we took our Olympus stylus tough 8010 under water camera.
you can swim around the walls of the fort but you can not swim in the moat for some reason.
The water is calm and warm enough for kids to swim and snorkel , but they should wear a life jacket.
For kids it is best to keep to the wall because in some areas the current can be a bit strong.
It is possible to snorkel around the whole key but beware of the currents.
It is areal adventure getting to the key. you can take a 2.5 hr boat ride or go by sea plane.
it is also possible to camp on the key but reserve a camping spot well in advance. There is no fresh water on the Key so bring all that you need with you.