Part of The US National Parks
- Where
- c. 70 miles west of Key West
Gulf of Mexico, Florida - Coordinates
- 24.6285° N
82.8732° W - Biome
- Coral keys & open water
- The fort
- 16+ million bricks, 16 acres
begun 1846, never finished - Status
- National Monument 1935
National Park 1992 - Best visited
- November–April
Sailed out to a fort that never finished and never fought, sitting in water so blue it seems like showing off. I came for the bricks. I stayed for the blue. The bricks, to their credit, did not take it personally. Item: swim beside the wall. Item: dry out on top of it. Item: repeat until the boat insists.
The short answer
The Dry Tortugas are a cluster of seven small islands about 70 miles west of Key West, Florida, protected since 1992 as Dry Tortugas National Park — a park that is almost entirely water. On Garden Key stands Fort Jefferson, the largest brick masonry structure in the Americas: more than 16 million bricks covering 16 acres, begun in 1846, worked on for three decades, and never finished. Ponce de León named the islands Las Tortugas for their sea turtles in 1513; sailors added the "Dry" as a warning that they hold no fresh water.
Why it's worth knowing
The scale is the first absurdity: a hexagonal fortress with walls up to 477 feet a side rising straight out of turquoise shallows, on an island so small the building occupies most of it. Everything — every brick, every worker, every drop of drinking water — came by ship. The fort's answer to the islands' dryness was to make its own walls a reservoir, with cisterns built into the foundations to catch rain by the hundreds of thousands of gallons.
The second absurdity is that none of it was ever used for its purpose. The fort was built to command the shipping channel into the Gulf; by the time its walls were up, rifled artillery had made brick fortresses obsolete. It was never completed, never armed to plan, and never attacked.
What the islands do instead is nature. The park is 99 per cent water, with living coral, seagrass, hundreds of documented shipwrecks, nesting sea turtles, and one of North America's great seabird colonies on the key next door.
The field notes
A prison instead of a fortress
The fort found its real use during the Civil War — not repelling ships but holding prisoners, mostly Union deserters. Its most famous inmate was Dr. Samuel Mudd, the physician convicted of conspiracy for treating John Wilkes Booth's broken leg after the Lincoln assassination. Mudd's medical work during a yellow fever outbreak at the fort helped earn him a pardon in 1869.
Look closely at the walls and the building tells its own history in colour: the lower courses were raised with brick shipped from the South before the war, the upper ones with darker northern brick afterwards, and the line between them is still visible in the walls.
Two lighthouses, one small empire of birds
The islands' first federal building was not the fort but a lighthouse, lit on Garden Key in 1826 to steer ships around the reefs; the fort was later built around it. A taller light followed on Loggerhead Key in 1858 and still stands. The Garden Key light was deactivated in 1924, having outlasted the fort's military career.
Next to Garden Key lies Bush Key, where sooty terns and brown noddies nest in extraordinary numbers each year — the key closes to visitors for the nesting season, and the birds' colony is one of the most important of its kind in North America.
A park that is mostly water
The land in Dry Tortugas National Park adds up to a rounding error; the park is the sea around it. More than 300 wrecks are documented in these waters, from Spanish galleon days to the age of steam, and the most accessible — the Windjammer, a iron-hulled sailing ship — can be snorkelled straight from a beach landing.
The moat wall around the fort doubles as the easiest snorkel in the park: a calm, shallow circuit past coral heads and reef fish, with the brick wall as a handrail. The islands sit far enough out that the water runs Caribbean-clear on most days.
- Arrive by sea, like everything here always has.
- Walk the whole top of the wall, saluting nobody.
- Count the arches until the number stops mattering. (Stopped at lunch.)
- Snorkel along the moat wall and greet whoever lives there now.
- Spare a thought for the lighthouse next door, which kept better watch than any cannon.
The colour line in the walls. The fort's lower courses are the warm red of southern brick shipped before the Civil War; the upper courses are the darker brick of northern yards, laid after. The whole national argument of the 1860s is recorded in the masonry, at the height where the war interrupted the work.
Tally, in the marginA building that changed its mind halfway up — I keep a list, it keeps a stripe. Kindred.
Getting there
Access is by the daily ferry from Key West, by seaplane, or by private boat; there is no bridge and no airstrip. The ferry crossing takes a little over two hours each way and books out well ahead in winter; the seaplane is faster and dearer. Day trips allow around four hours at the fort — enough for the walls, a swim and the moat snorkel.
A small number of campsites on Garden Key allow overnight stays for the self-sufficient: carry in everything, including all water — the islands are as dry as the name says — and carry everything out. November to April brings the calmest seas and the best visibility; summer brings heat, and the season's storms can close the crossing at short notice.
Common questions
What is Fort Jefferson?
Fort Jefferson is a coastal fortress on Garden Key in Dry Tortugas National Park, Florida, and the largest brick masonry structure in the Americas, built from more than 16 million bricks over 16 acres. Construction began in 1846 and continued for about three decades, but the fort was never finished, never fully armed, and never attacked.
Why are they called the Dry Tortugas?
Ponce de Leon named the islands Las Tortugas, the turtles, in 1513 for the sea turtles found there. Sailors added the word Dry to charts as a warning that the islands hold no fresh water. The name is one of the oldest European place names still in use in the United States.
Who was imprisoned at Fort Jefferson?
During and after the Civil War, Fort Jefferson served as a military prison holding mostly Union deserters. Its most famous prisoner was Dr. Samuel Mudd, convicted of conspiracy for treating John Wilkes Booth after the Lincoln assassination. Mudd's service during a yellow fever outbreak at the fort contributed to his pardon in 1869.
How do you get to the Dry Tortugas?
The Dry Tortugas lie about 70 miles west of Key West and are reached by daily ferry, by seaplane, or by private boat. The ferry takes a little over two hours each way. There are no roads, no bridge and no airstrip, and day visitors typically get around four hours on Garden Key.
Can you snorkel at Dry Tortugas National Park?
Yes. The park is 99 per cent water, and the easiest snorkelling runs along the fort's moat wall directly off the beach on Garden Key. The Windjammer shipwreck is also accessible to snorkellers, and the park's waters hold living coral reefs, seagrass beds and hundreds of documented wrecks.
Can you stay overnight at the Dry Tortugas?
Yes. A small primitive campground on Garden Key allows overnight stays for visitors who carry in all supplies, including every drop of water, and carry all waste out. The islands have no fresh water, no shops and no services after the day boats leave, which is precisely the appeal.