Dry Tortugas National Park

Dry Tortugas National Park is the reason many travelers come to Key West in the first place. Seventy miles west of the island, beyond the end of the Keys, a cluster of small islands and shoals holds one of the strangest sights in American history: Fort Jefferson, a colossal six-sided brick fort built on Garden Key from the 1840s onward to guard the Gulf shipping lanes, its walls rising straight out of a moat and the clearest water most visitors will ever see. The park is about ninety-nine percent water, there is no road, and access is by boat or seaplane only — which keeps it uncrowded, wild, and deeply memorable. The standard visit is the Yankee Freedom day trip, the park's authorized ferry concession: a high-speed catamaran departs the Key West ferry terminal in the early morning, crosses open water in a little over two hours, and gives you roughly four hours on Garden Key, with breakfast, lunch, snorkel gear, and a guided fort tour included in the fare. The other way in is by seaplane — a low, forty-minute flight over the flats and shipwrecks that is a highlight in itself, with half-day or full-day options and far fewer seats. On the island: walk the fort's three tiers of arched casemates, climb to the top for the view across the moat and the islands, snorkel along the moat wall where coral and tropical fish crowd the old brick, and lie on the small beaches. Birders come in spring for the sooty tern colony on Bush Key and the migrants that drop onto the island exhausted from the Gulf crossing.

The history is gripping. Ponce de Leon named the islands Las Tortugas for the sea turtles in 1513; mariners added "Dry" because there is no fresh water. The US Army began Fort Jefferson in 1846 as part of a chain of coastal forts, and it became the largest masonry structure in the Western Hemisphere — some sixteen million bricks — yet it was never finished, its foundations settling into the coral and newer rifled artillery making brick forts obsolete before the last tier was done. During the Civil War it held Union deserters and prisoners; its most famous inmate was Dr. Samuel Mudd, convicted for setting John Wilkes Booth's broken leg, who earned a pardon after treating the garrison through an 1867 yellow fever epidemic. The fort was abandoned by the Army in 1874, declared a national monument in 1935, and the park was created in 1992. The moat wall has needed repeated repairs after hurricanes; a dredging and wall project in 2024 temporarily closed parts of the beaches and campground before reopening.

Booking strategy: the ferry sells out weeks ahead in the winter and spring high season and on holiday weeks — book as soon as your dates are set, and check the operator's day-of updates, because rough seas can cancel or reroute trips. The park's own entrance fee applies to visitors sixteen and over and is handled through the ferry and seaplane operators for their passengers. Seaplane seats are even scarcer and pricier; they suit travelers who are short on time or prone to seasickness on a long crossing (the ferry can be bumpy in winter northerlies — take a remedy before boarding). Camping on Garden Key is possible in a small primitive campground for the self-sufficient, with ferry transport booked separately and early; it is unforgettable for the night sky.

On the day: take the guided fort tour first for orientation, then decide between snorkeling and exploring. The best snorkeling runs along the outside of the moat wall from the beach — look for coral heads, sergeant majors, parrotfish, and the occasional nurse shark resting under the ledges — and the water can be cool in winter, so a rash guard helps. Bring reef-safe sunscreen, a hat, water, and cash or card for the small gift shop; there is no other food on the island beyond what the ferry serves. Visitors with mobility limitations should know the fort's upper levels involve stairs and uneven brick. Whatever you do, leave time to stand on the top tier and look around: brick, water, and nothing else for seventy miles. It is the kind of place that makes the trip.