Accessible only by boat or seaplane, the Dry Tortugas National Park is situated in Florida, about 112.6 km (70 mi) west of Key West. It’s a cluster of seven coral reefs, composed into a national park in 1992 to protect the marine and birdlife that live in this near-perfect tropical ecosystem. The park is 647 km2 (249.8 sq mi), only 0.37 km2 (0.14 sq mi) of which lie above water. The islands themselves contain no natural surface freshwater, which is why they are called ‘dry’.
An annual spectacle found nowhere else in the US is the appearance of over 100,000 sooty terns which come here to nest and breed between March and September. The endangered green sea turtle and the threatened loggerhead turtle bury their clutches of eggs on the protected beaches in summer.
The park also preserves a strong historic and cultural legacy, including shipwrecks, tales of sunken treasure and Fort Jefferson, which is situated on Garden Key. Construction of this huge structure began in 1846 to protect shipping lanes in the Gulf of Mexico, but it was never finished. Despite this, the structure is the largest masonry structure in the Western Hemisphere, containing over 16 million bricks and 2,000 archways.
There are around 80,000 visitors to the park annually, for saltwater fishing, bird-watching and camping. The pristine waters make the islands a real attraction for scuba divers and snorkelers, not just for the varied marine wildlife and coral reefs, but also because the area contains the largest concentration of historically significant shipwrecks from the 17th century to date.