High Quality Content by WIKIPEDIA articles! The Dry Tortugas are a small group of islands, located at the end of the Florida Keys, USA, about 70 miles west of Key West, and 37 miles west of the Marquesas Keys, the closest islands. Still further west is the Tortugas Bank, which is completely submerged. The first Europeans to discover the islands were the Spanish in 1513 by explorer Juan Ponce de León. They are an unincorporated area of Monroe County, Florida and belong to the Lower Keys Census County Division. With their surrounding waters, they constitute the Dry Tortugas National Park.