Skip to main content

Fort Jefferson, Fla.

Land ho! It’s that exciting moment when a dark smudge appears on the horizon between the Florida Keys’ turquoise waters and azure sky. The smudge grows larger and more distinct, morphing into not a palm-fringed island or mangrove tangle but a massive brick fort nearly covering 16-acre Garden Key. It’s incongruous and awe-inspiring in this endless expanse of ocean.

The massive fort has 8-foot-thick masonry walls.

This is Fort Jefferson, the centerpiece of Dry Tortugas National Park, a 100-square-mile wonderland of marine life, coral and seven dots of land 68 miles west of Key West. These subtropical islets, discovered and named “tortugas” (turtles) by Ponce de Leon in 1513, provide some of the Keys’ best diving and snorkeling on the world’s third-largest barrier reef.

Like Ernest Hemingway, some come here to fish, though anchoring, fishing and collecting are prohibited in the Species Protection and Research Natural Areas. Others follow John James Audubon’s example to see more than 200 species of migrating and resident birds. Magnificent frigate birds frequently soar overhead, and some 80,000 sooty terns, 4,500 brown noddies and masked boobies nest here. Endangered sea turtles lumber ashore to lay their eggs.

Boats are welcome, but strict regulations allow anchoring only in sand and overnighting to within a mile of Fort Jefferson. Obtain a free seven-day permit from rangers on Garden Key; it’s required even for dinghies and kayaks. In the Research Natural Area, including Loggerhead Key, you must pick up a mooring buoy. You can use Loggerhead Key beach, but the dock, lighthouse and other buildings are off-limits. Cruisers must be self-sufficient. Garden Key has some facilities but no lodgings, water, food, supplies, fuel or medical services.

Don’t want to deal with the currents, winds and coral in your own boat? The Yankee Freedom III catamaran ( carries as many as 100 passengers on daily cruises that include breakfast, lunch and snorkeling gear.

Though I enjoy the wildlife, the isolated pristine waters and lounging on the sugar-white sands, it’s the Western Hemisphere’s largest brick building that fascinates me. When construction began in 1846, Fort Jefferson was a state-of-the-art “Gibraltar of the Gulf” in the chain of fortifications from Maine to Florida. It protected the essential 19th-century shipping lanes between East Coast cities and Gulf Coast ports. During the Civil War, Union vessels blockading Southern ports were based here. Construction ceased in 1874 when the newly invented rifled cannon could penetrate the fort’s 8-foot-thick masonry walls. Into the 1940s, Fort Jefferson served as a military coaling station.

Image placeholder title

You’ll learn all this and more on a 45-minute guided walk. I prefer following the hexagonal fort’s self-guided tour, when I can hear nothing but my footfalls on the gravel, buttonwood trees rustling in the breeze and the cacophony of nesting noddies and boobies on adjacent Bush Key and Long Key. I try to imagine the deprivation that the fort’s 2,000 residents endured. They had a bakery and desalinization plant, but there was scant rainfall, supply ships were irregular, and the cisterns and septic system cracked as the fort sank under its own weight. Walking through some of the fort’s 2,000 arches, I sight vistas of the turquoise sea through the cannons’ firing ports. Replacement bricks and non-rusting composite doors are being installed. Salt air and the wet environment long ago destroyed the original iron doors and attached masonry.

Brick stairways spiral up 45 feet to the 1876 Garden Key lighthouse atop the walls. Decommissioned in 1921, it now shines as a harbor light. The six 15-inch Rodman cannons — the largest collection in the world — remain; most of the fort’s armaments were sold for scrap in 1900.

Other stairways permeate the inner reaches of “America’s Devil’s Island” to the cells of Confederate prisoners. Dr. Samuel Mudd was convicted of conspiring to help John Wilkes Booth, President Abraham Lincoln’s assassin, escape capture. He was imprisoned here for nearly four years. President Andrew Johnson later pardoned Mudd.

Out in the parade ground’s fresh air you can examine the hot shot furnace, two of the 37 powder magazines, barracks’ ruins and the 1826 lighthouse foundation. Stroll the 0.6-mile moat wall to see colorful tropical fish swimming among the sea grass and corals in the crystal-clear shallows. Or snorkel prime spots near or far.

Fort Jefferson is only open during daytime hours ($5 a person), but from your own boat you can experience the magic of this mirage-like fortification bathed in moonlight.

Download regulations and other information at

See related articles:

- Island Summer

- Monhegan Island, Maine

- Stonington, Maine

- Martha's Vineyard, Mass.

- Block Island, R.I.

- Tangier Island, Va.

- Smith Island, Md.

July 2013 issue