Fort JeffersonAbout Fort Jefferson
Fort Jefferson is a large mid‑19th‑century coastal fortress on Garden Key in the Dry Tortugas, about 70 miles west of Key West, Florida. Built of brick as a coastal defence work, it was never fully completed but remains one of the largest brick masonry structures in the Americas.
The fort contains extensive casemate rooms and a surrounding moat; ranger‑led tours interpret its military construction, Civil War use and later role as a military prison. The fort and the surrounding coral reefs are the focal points for visitors who arrive by boat or seaplane from Key West.
Visitors commonly combine a fort tour with snorkeling on nearby reefs, birdwatching and limited island camping; facilities on Garden Key include a small campground and day‑use areas. The park is managed as Dry Tortugas National Park and access is regulated to protect the marine and historic resources.
Garden Key lies on a low coral outcrop in the Gulf of Mexico and is surrounded by reef habitat within a large marine park.
- Location and access: Located on Garden Key in Dry Tortugas National Park, about 70 miles (113 km) west of Key West, Florida; access is by boat or seaplane from Key West.
- Size and history: Construction began in the mid 19th century and the unfinished fort is one of the largest brick masonry structures in the Americas; it was used as a Union base during the Civil War and later as a military prison.
What to See#
- Fort Jefferson structure: The fort itself - a massive brick coastal bastion with multi‑tiered casemates and a surrounding moat, open for ranger‑led tours.
- Garden Key campground and visitor facilities: Garden Key campground and visitor areas on the island that provide day‑use picnicking, camping by permit and direct access to snorkeling sites.
- Reef and snorkel sites: Shallow reefs and drop‑off snorkel sites around the Dry Tortugas, popular for coral and fish watching directly offshore from Garden Key.
Best Time to Visit Fort Jefferson
Late winter through spring is the most reliable period for calm seas, good snorkelling and scheduled ferry services.
Weather & Climate near Fort Jefferson
Tropical climate with hot summers (peaking in August) and warm winters (coldest in January). Temperatures range from 18°C to 33°C. Abundant rainfall (1222 mm/year), wettest in June.
| Month | Comfort | Temp | Feels | Rain | Sky | Humidity | Wind | UV | Daylight |
|---|---|---|---|---|---|---|---|---|---|
| January | - | 18° - 24° | 21° | 85 mm | - | - | 4.1 m/s | - | - |
| February | - | 18° - 24° | 21° | 62 mm | - | - | 4.3 m/s | - | - |
| March | - | 19° - 25° | 22° | 63 mm | - | - | 4.5 m/s | - | - |
| April | - | 21° - 27° | 24° | 51 mm | - | - | 4.2 m/s | - | - |
| May | - | 23° - 30° | 26° | 88 mm | - | - | 3.7 m/s | - | - |
| June | - | 25° - 32° | 28° | 157 mm | - | - | 3.1 m/s | - | - |
| July | - | 25° - 33° | 29° | 130 mm | - | - | 3.0 m/s | - | - |
| August | - | 25° - 33° | 29° | 154 mm | - | - | 2.7 m/s | - | - |
| September | - | 25° - 32° | 29° | 157 mm | - | - | 3.2 m/s | - | - |
| October | - | 24° - 30° | 27° | 116 mm | - | - | 3.7 m/s | - | - |
| November | - | 22° - 27° | 24° | 73 mm | - | - | 4.1 m/s | - | - |
| December | - | 19° - 25° | 22° | 86 mm | - | - | 3.9 m/s | - | - |
How to Get to Fort Jefferson
Fort Jefferson is on Garden Key in Dry Tortugas National Park, about 70 miles west of Key West, Florida. Access is by scheduled ferry service (Yankee Freedom III), private boat, or seaplane from Key West. Ferries depart from Key West and include a day trip with stops for snorkelling; seaplane charters offer shorter visits.
Tips for Visiting Fort Jefferson
- Book ferry (Yankee Freedom III) or seaplane seats well in advance - trips often sell out, especially in winter and spring.
- Bring cash or card for concessions on Garden Key; pack sun protection and insect repellent.
- Snorkel early in the day before winds pick up; clear water lies near the reef fringes but currents can be strong.