Getting to Dry Tortugas National Park - located 70 miles west of Key West - takes some advanced planning, but it's well worth the trip. Named by Ponce De Leon in 1513 after the abundance of sea turtles, the park encompasses 100 square nautical miles around a group of seven islands. The islands are populated with coral reefs, exotic tropical fish, giant groupers, rare birds and, of course, turtles, including loggerhead green, hawksbill, and leatherback sea turtles. Garden Key, the largest island in the group, holds historic Fort Jefferson. Developed in 1846 to protect the Gulf of Mexico, it was never actually finished. But its 16 million bricks make it the largest masonry structure in the Western Hemisphere. There's a small pier for loading and unloading supplies, some primitive campsites, and a visitor center, but boaters have to anchor overnight. Don't expect to find gas, food or even fresh water in the Dry Tortugas.