Bois Blanc Island is an island in Lake Huron within Bois Blanc Township, Mackinac County, Michigan. The island covers about 34 sq mi (88 km2) and is about 12 miles (19 km) long, 6 miles (9.6 km) wide and has 6 lakes. It lies southeast of Mackinac Island and almost due north of the city of Cheboygan.