Dry Tortugas National Park (Fort Jefferson): Ferry & Seaplane Guide

Located 113 kilometres (70 miles) west of Key West in the Gulf of Mexico and accessible only by boat or seaplane, Dry Tortugas National Park is one of the most remote national parks in the United States. Named Las Tortugas ('The Turtles') in 1513 by Spanish explorer Juan Ponce de León after catching 160 sea turtles, mariners soon added 'Dry' on charts to warn ships that the seven coral islands held zero fresh drinking water. Rising from the turquoise water on 16-acre Garden Key is Fort Jefferson, begun in 1846 with over 16 million bricks, making it the largest masonry building in the Western Hemisphere.

1. How to Get There: The Yankee Freedom Ferry vs Seaplane

Because daily passenger numbers are strictly capped, book three to six months before your trip (check current fares and schedules on the official operators' sites, or join the early-morning standby line at the terminal):

• The Official Yankee Freedom III Catamaran Ferry: departs in the morning from the Key West Ferry Terminal (100 Grinnell Street) near the Historic Seaport. The 2-hour 15-minute crossing includes breakfast, lunch, snorkel gear, a ranger-led tour and 4.5 hours on the island; national park pass holders receive a fee discount at check-in. Take a non-drowsy motion-sickness tablet before boarding if winds exceed 15 knots.
• Key West Seaplane Adventures (Half-Day or Full-Day): flies up to 10 passengers in a Turbine Otter floatplane at a low 150-metre altitude, taking 40 minutes each way. You spot shipwrecks, sea turtles, sharks and dolphins through clear water before splashing down beside Fort Jefferson ahead of the ferry crowds.

2. How to Spend Your Time at Fort Jefferson

1. Walk the Full 1-Kilometre Outer Moat Wall: stroll around the narrow concrete moat wall surrounded by turquoise water on both sides, wearing water shoes and reef-safe sunscreen.
2. Tour the Three-Tiered Brick Casemates & Dr. Samuel Mudd's Cell: during the Civil War, Fort Jefferson held 2,000 Union prisoners, including Dr. Samuel Mudd, imprisoned in 1865 after treating Abraham Lincoln's assassin, John Wilkes Booth.
3. Snorkel the Moat Wall, South Coaling Dock Ruins & Bush Key Sandspit.