The Porcupine Mountains are home to the most extensive stand of old growth northern hardwood forest in North America west of the Adirondack Mountains, spanning at least 31,000 acres (13,000 ha). In these virgin forests, Sugar Maple, American Basswood, Eastern Hemlock, and Yellow Birch are the most abundant tree species.

Porcupine Mountains State Park was established in 1945 to protect this large stand of old-growth forest, much of "maple-hemlock"type. In 1972, Michigan passed the Wilderness and Natural Areas Act. This act gave the park the new designation of the Porcupine Mountains Wilderness State Park. The facilities provided by the park include an extensive network of backcountry trails for hiking and wilderness backpacking, rustic trailside cabins, modern campgrounds, swimming and boating areas, and various interpretive programs led by park rangers. The North Country Trail passes through the park, making up a portion of the 87 miles (140 km) of hiking trails. In the winter, a ski area also operates within the park. Because of the copper mining history of the park, it is a cooperating unit of Keweenaw National Historical Park. In 1973, numerous scenes from the movie "Cocoon" were filmed in the park. Most notable out of these, is the pool scene.

Fauna in the park includes MooseGray WolfWhite-Tailed DeerCoyotesGray Andred Foxes, River Otters, BeaverFisherMarten , MinkBobcatsLynxBlack Bears, and Porcupines.