49 Fun Facts About Dry Tortugas National Park

The Dry Tortugas lie in which body of water, about 70 miles west of Key West?

Gulf of Mexico: the islands sit at its gateway beside one of the world's busiest shipping lanes, which is why the Army chose their harbour for a giant fort.

Apart from boats, what is the only way for visitors to reach Dry Tortugas National Park?

Seaplane: the islands have no runway and no road, so the planes from Key West touch down on the water and moor beside the fort.

Roughly how many bricks went into the walls of Fort Jefferson?

About 16 million bricks, laid around a core of coral concrete, went into the fort, and their weight has been pressing the walls unevenly down into the sand ever since.

Which explorer, the first European known to reach the Dry Tortugas, gave the islands their name in 1513?

Juan Ponce de León called them Las Tortugas, 'the turtles', for the sea turtles his crew found there, only weeks after he had landed in Florida and named that too.

Why are the Dry Tortugas called 'Dry'?

They have no surface fresh water: chart-makers added the word to warn passing crews not to count on refilling their casks, and visitors still have to carry in all they drink.

More than 99 percent of Dry Tortugas National Park consists of what?

Open water covers all but a fraction of a square mile of the 101-square-mile park, which is why rangers say the best way to see it is to get in and swim.

Which feature, repeated row upon row in brick, is the hallmark of Fort Jefferson's gun galleries?

Arches: each gun room is a brick vault strong enough to carry a second tier of cannon above it, and an early Park Service study called the fort a splendid example of arch construction.

What sometimes links Bush Key to Garden Key, letting visitors walk between the two Dry Tortugas islands?

A shifting sandbar: storms and currents build it up and cut it through again, so in some years Bush Key is a short walk from the fort and in others it takes a kayak.

What has been forcing the bricks out of Fort Jefferson's outer walls for more than a century?

Rusting iron shutters: built into the gunports to shield the crews, they swelled as the salt air corroded them and have pushed whole sections of the brick facing off the walls.

After 30 years' work, how did the Army leave Fort Jefferson?

Unfinished: with the walls sinking under their own weight and military technology moving on, the work was never completed, and the Army pulled its garrison out in 1874.

In July 1847 seven enslaved workers fled the Fort Jefferson site by boat; how did their escape end?

Caught and sent back: the seven were seized in the Keys within days, the two ringleaders were dismissed and the other five returned to the works, where their wages went on being paid to their owners.

Seen from the air, Fort Jefferson's walls trace which shape?

Hexagon: six brick walls meet at corner bastions that jut out so the defenders could fire along the face of the wall next door.

How did Fort Jefferson, built to mount hundreds of heavy guns, fare in battle?

No enemy attacked it: the fort worked as a deterrent, and its harbour spent the Civil War sheltering the Union warships that were blockading Southern ports.

What went wrong with the rainwater cisterns built into the walls of Fort Jefferson?

The stored water turned salty: salts leached out of the sand filters, or seawater seeped in where the settling walls cracked the tanks, and the garrison came to depend on steam condensers that distilled seawater.

Dr Samuel Mudd was imprisoned at Fort Jefferson for helping which assassin, whose broken leg he had set?

John Wilkes Booth rode to Mudd's Maryland farm hours after the shooting; Mudd set the leg, then told investigators he had not recognised his patient, a lie that helped convict him.

How did Dr Samuel Mudd try to escape from Fort Jefferson in 1865?

Hid aboard a supply ship: two months into his sentence he slipped onto the transport Thomas A. Scott and lay under planks in the hold, was soon found, and was put in irons in a cell known as the dungeon.

What did Dr Mudd do at Fort Jefferson that helped win his pardon?

Treated patients during a yellow fever epidemic: when the post surgeon died in 1867, the prisoner took charge of the hospital, and the garrison's soldiers signed a petition for his release that credited him with saving lives.

Which president pardoned Dr Samuel Mudd in 1869?

Andrew Johnson pardoned him less than a month before leaving office; Mudd, who had escaped the gallows by a single vote, went home to Maryland, but his conviction was never overturned.

During the Civil War, Fort Jefferson served mainly as a prison for Union soldiers convicted of what?

Desertion: the Union shipped its captured deserters to the remote fort, where the convicts were put to hard labour on the very walls they were locked inside.

Which Civil War-era advance made Fort Jefferson's thick brick walls obsolete while they were still going up?

Rifled artillery: in 1862 Union rifled guns battered a breach in the brick walls of Fort Pulaski in Georgia in about 30 hours, showing that no masonry fort could hold out any longer.

Which US Navy warship called at the Dry Tortugas in 1898 just before its fateful voyage to Havana?

USS Maine blew up in Havana harbour three weeks after she arrived, killing more than 250 of her crew, and 'Remember the Maine' became the cry that carried America into war with Spain.

From 1904 to 1939 the Carnegie Institution ran what on Loggerhead Key in the Dry Tortugas?

A marine biology laboratory: scientists came each summer to study the reefs and left before hurricane season, and its work included some of the first underwater colour photographs.

Which president used the Antiquities Act to make Fort Jefferson a national monument in the depths of the Depression?

Franklin D. Roosevelt proclaimed the monument in January 1935, and within months New Deal relief crews were at work shoring up the crumbling fort.

In 1908 the Dry Tortugas became a federal bird reserve, created to stop the collecting of what?

Eggs: the order shut out the collectors who raided the islands' seabird rookery, and the colony it saved now draws tens of thousands of nesting birds every year.

During the 1995–96 government shutdown, which 'micronation' staged an 'invasion' to reopen Fort Jefferson?

The Conch Republic, Key West's half-serious breakaway 'nation', set out with a cheque for a day of the park's running costs and a plan to declare the fort open, because the closure was costing the town's tour operators dearly.

Who found the 1622 wreck of the treasure galleon Atocha between Key West and the Dry Tortugas in 1985?

Mel Fisher had found the first traces of the wreck in the 1970s, and Florida claimed it; he fought the state to the US Supreme Court and won in 1982, three years before his divers reached the main treasure.

The crew of HMS Tyger, wrecked in the Dry Tortugas in 1742, escaped 700 miles in small boats to which British colony?

Jamaica: the castaways tried and failed to seize a Spanish ship, then crossed enemy waters in small boats to Port Royal; archaeologists confirmed the identity of the wreck in 2024.

Birdwatching at the Dry Tortugas peaks with migration in which month?

April: the islands lie on a main flyway between North and South America, and at the height of the northbound passage thousands of songbirds and other migrants stop there to rest.

Dry Tortugas National Park holds the only large nesting colony in the continental United States of which seabird?

Sooty tern: tens of thousands crowd onto Bush Key to nest, so the island is closed to visitors for most of the year and birders watch the colony from the walls of the fort.

What killed 96 percent of the shallow-water corals surveyed at the Dry Tortugas in January 1977?

A cold wave: the Arctic outbreak that gave the Miami area its only known trace of snow also pushed 14 °C water over the reef, far colder than its shallow corals could survive.

Which lone reptile lived around Fort Jefferson for some 14 years until it was moved in 2017?

An American crocodile kept to itself for years, then took to the swimming area beside the fort, and once visitors began trying to approach it, it was captured and released on the mainland.

Which catamaran is the official ferry that carries visitors from Key West to Dry Tortugas National Park?

Yankee Freedom III belongs to the Yankee Fleet, better known for whale-watching trips out of Gloucester, Massachusetts, which is how a Key West ferry came by its New England name.

Where may visitors stay overnight on land in Dry Tortugas National Park?

Campground: a primitive one beside the fort is all there is, with a few first-come sites, grills and compost toilets, and campers must bring in everything they will need.

In 2007 Dry Tortugas National Park set aside nearly half its waters as what?

A no-take research natural area: nothing may be fished or collected there and boats may not drop anchor, which gives scientists an untouched reef to compare with the fished waters next door.

The homemade boats called 'chugs' that sometimes land at the Dry Tortugas carry migrants from which country?

Cuba: until 2017 a Cuban who reached US soil, these remote keys included, was generally allowed to stay, while those stopped at sea were usually returned to Cuba.

The first underwater colour photographs, taken at the Dry Tortugas in 1926, were made for which magazine?

National Geographic: its photographer and a fish scientist lit each shot by setting off a pound of magnesium flash powder on a boat floating above the diver.

Which iron structure has stood on top of the walls of Fort Jefferson since 1876?

A lighthouse: hurricanes had battered the old brick tower inside the fort, so its replacement was built of iron plate on top of a bastion, where it still stands.

What separates the walls of Fort Jefferson from the open sea on every side?

A moat: a low outer wall rings the fort and holds a band of seawater that was meant to keep landing parties off the walls and still breaks the force of the waves.

Which famous naturalist visited the Dry Tortugas in 1832, long before the fort was built?

John James Audubon came in 1832 to see the seabird rookery for himself, and the zoologist Louis Agassiz followed in 1858, two visits the park still tells its visitors about.

Which hurricane passed over the Dry Tortugas in August 2004, hours before its Category 4 landfall in southwest Florida?

Charley crossed the islands on the morning of 13 August 2004, wrecking their weather instruments, then deepened at a startling rate and tore into Punta Gorda about eight hours later.

What became of Bird Key, where Fort Jefferson buried its Union dead?

It disappeared into the sea in 1935, lost to a hurricane: the keys are only sand and coral rubble, and storms have cut their number from eleven to seven.

Why was Fort Jefferson built with a furnace for heating cannonballs red-hot?

To set wooden ships alight: the 'hot shot furnace' that still stands inside the fort was built to roast solid shot to a cherry red, which gunners would carry to the guns in a ladle.

Dry Tortugas National Park shares its superintendent with which other park?

Everglades: one superintendent runs both parks, and much of the museum collection from the Tortugas is kept on the mainland in a collections centre at Everglades rather than at the fort.

Which invasive fish from the Indo-Pacific has reached the reefs of Dry Tortugas National Park?

Lionfish: loose in the Atlantic since the 1980s, they eat the young of native fish and compete with snapper and grouper, so the park drew up a plan for staff to survey chosen reefs and remove them.

In 1889 the Army handed Fort Jefferson to the Marine Hospital Service for use as what?

A quarantine station: ships with infection aboard were sent to the empty fort to be disinfected, among them transports carrying American troops home from the war with Spain.

Before the Civil War, the bricks for Fort Jefferson came mainly from kilns near which Florida port?

Pensacola: the Army's engineers judged its bricks better able to stand the subtropical weather than Northern ones, though once the war began they had to fall back on bricks shipped from New England.

The ruined pilings beside Fort Jefferson, now a favourite snorkelling spot, once held the Navy's stores of what?

Coal: around 1900 the Navy built piers and sheds there to refuel its steam warships, and when a hurricane wrecked them it chose not to rebuild, leaving the pilings to the fish.

Fort Jefferson belonged to the 'Third System' of coastal forts, which Congress began funding after which war?

The War of 1812, in which British troops burned Washington, pushed Congress to pay for a chain of brick and stone forts along the coast, and Fort Jefferson was one of the largest of them.

Montgomery Meigs, who drew Fort Jefferson's plans, later oversaw the building of which landmark's dome?

The United States Capitol: Meigs oversaw its new dome and wings in the 1850s, then a quarrel with the Secretary of War got him exiled in 1860 to the Tortugas fort he had drawn as a lieutenant.