Dry Tortugas National Park is a national park in the USA about 68 statute miles (109 km) west of Key West in the Gulf of Mexico. The park preserves Fort Jefferson and the seven Dry Tortugas islands, the westernmost and most isolated of the Florida Keys. The archipelago's coral reefs are the least disturbed of the Florida Keys reefs.
The park is noted for abundant sea life, tropical bird breeding grounds, colorful coral reefs and legends of shipwrecks and sunken treasures. The park's centerpiece is Fort Jefferson, a massive but unfinished coastal fortress. Fort Jefferson is the largest masonry structure in the Western Hemisphere, and is composed of over 16 million bricks. Dry Tortugas is unique in its combination of a largely undisturbed tropical ecosystem with significant historic artifacts. The park is accessible only by seaplane or boat and averages 60,000 visitors each year. Activities include snorkeling, picnicking, birdwatching, camping, scuba diving, saltwater fishing and kayaking.