Harbor Island National Wildlife Refuge is a 695-acre, horseshoe-shaped island in Potagannissing Bay north of Drummond Island, Michigan. Acquired in 1983 by the United States Fish and Wildlife Service from The Nature Conservancy, it was set aside for protection as part of the national wildlife refuge system. The island lies in waters known for freshwater fish such as lake trout and whitefish, while the refuge supports balsam, paper birch, cedar, sugar maple, and red oak. With no bridges to the island, access is by boat, and its sheltered harbor is a well-known anchorage for small craft. Administration is handled from Seney National Wildlife Refuge.