Big Bay State Park is a state park of Wisconsin, United States, on Madeline Island, the largest of 22 Apostle Islands in Lake Superior. The 2,350-acre park has picturesque sandstone bluffs and caves and a 1.5-mile-long sand beach. It encloses unique habitat types including lakeside dunes, sphagnum bogs, and old-growth forest. Bald eagles return annually to the park to nest and rear offspring.