Located in Lake Superior off the Bayfield Peninsula, the Apostle Islands National Lakeshore includes 21 of the 22 islands making up the Apostle archipelago as well as a 12-mile segment of mainland shoreline. The islands are composed of eroded Precambrian sandstone and display a variety of formations and sandscapes, including sea caves, sandspits, and dunes. Habitats are mostly forested and combine elements of hemlock-white pine-northern hardwood forest and boreal forest. Forests are largely mature second growth with some areas of old growth. Bogs, streams, alder thickets, and pine savanna also are present.
The Apostle Islands are an outstanding concentration area for migrating birds, especially in fall, hosting tens of thousands of passerines and raptors, particularly falcons. The islands also contain important nesting habitat for colonial waterbirds and bald eagles, and host a variety of breeding songbirds, including black-throated green warbler and Nashville warbler.