The Dry Tortugas are a small group of islands, located in the Gulf of Mexico at the end of the Florida Keys, United States, about west of Key West, and 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, led 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.