Fort Jefferson occupies two-thirds of Garden Island, one of the archipelago called the Dry Tortugas which lie 68 miles west of Key West in the Gulf of Mexico. You can’t drive or hike here; your only access is by sea or air.

The old fort is a massive structure of 16 million bricks, and was never fired upon or engaged in battle of any kind except for an outbreak of yellow fever. Famous as the prison that held the famous Dr. Mudd who was implicated in the assassination of Abraham Lincoln — the doctor having set the broken leg of John Wilkes Booth — the fort is now operated as a very isolated national park museum.

Its arches and vaults are today echoing the whispers of awed visitors and the marching feet of re-enactors and museum staff.

The campground next to the old fort is very small, so reservations are essential. There are no provisions other than restrooms, so campers must carry with them everything that they will need for their stay.

After exploring the fort, my favorite activity while at the Dry Tortugas was the snorkeling on the reefs that surround the island, populated by colorful sun fish, angel fish, reef sharks, nurse sharks, spotted rays, barracuda and a fair-size enclave of lobsters.

How to get there: From the southern tip of Florida, drive 175 miles west on the Florida Keys highway – Florida State Road A1A – to Key West. At the harbor board either the fast catamaran shuttle boats — which make the trip out in about 2 hours one way – or book the seaplane flight. Tickets and campsites should all be reserved in advance along with hotels or campground sites in Key West or nearby.

The Dry Tortugas are a national park and are managed by the National Park Service.