Loggerhead Key is an uninhabited tropical island within the Dry Tortugas group of islands inside the Gulf of Mexico. At approximately 49 acres in size, it is the largest island of the Dry Tortugas. Despite being uninhabited, the island receives visitors, such as day visitors and campers. The island only has a few built structures, including the Dry Tortugas Light and a lightkeeper's house that was constructed in the 1920s. The island has drinking water derived using desalination technology and solar power. The Carnegie Marine Biological Laboratory operated on Loggerhead Key from 1904 to 1939.