Dry Tortugas National Park is a 100-square mile park of seven small islands and open sea. It is about 70 miles west of Key West and is only accessible by boat or seaplane. The main destination of the park is the beautiful Fort Jefferson, one of the largest forts built in the 19th century in the United States built on Garden Key. Visit the island to explore the fort and stay the night in the island's campground. 3 miles away is Loggerhead Key, where you can see the lighthouse and the historic Carnegie Laboratory for Marine Ecology. The national park is also home to a huge variety of marine life and coral reefs. In fact, the park was named for the sea turtles who call this area home. Here you will find some of the best snorkeling and diving in the state.