Isle Royale National Park, island national park located in northwestern Lake Superior, northwestern Michigan, U.S. Established in 1931, the park has an area of 893 square miles (2,313 square km) and includes Isle Royale, the largest island in Lake Superior, measuring 45 miles (72 km) long and 9 miles (14 km) across. Its forested wilderness, with streams and inland lakes, hosts more than 200 species of birds. Travel is possible only on foot or by canoe, and ferry service is available from Minnesota and the Upper Peninsula of Michigan. The park became part of the National Wilderness Preservation System in 1976, and it was designated a UNESCO World Network Biosphere Reserve in 1980.