[4] They 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).

[6] A second ridge farther inland, on the other side of Lake of the Clouds, includes Summit Peak, the highest point in the mountains at 1,958 feet (595 m).

In these virgin forests, sugar maple, American basswood, eastern hemlock, and yellow birch are the most abundant tree species.

Endangered, threatened and special concern species found in the Porkies include small blue-eyed mary, ram's head ladyslipper, Hooker's fairy-bells, slender cliff brake, male fern, gray wolf, wood turtle, peregrine falcon, merlin, and bald eagle.

[6] Porcupine Mountains State Park was established in 1945 to protect the area's large stand of old-growth forest, much of it of the "maple-hemlock" type.