Federation Forest State Park (18 mi. west of Enumclaw [1] on Hwy. 410, 360/663-2207, www.parks.wa.gov [2]) has 619 acres of old-growth forest along the White River. Amid the virgin timber, an interpretive center (summer Wed.–Sun. 9 a.m.–4 p.m., closed winters) houses displays on plants and animals in the forest.
The park contains 11 miles of hiking trails, including two short interpretive paths and remnants of the historic Naches Trail, a pioneer trail that connected eastern Washington with Puget Sound. Federation Forest is also popular for fishing and picnicking; there’s no camping in the park.
Links:
[1] http://www.moon.com/destinations/washington/south-cascades/cle-elum-area/enumclaw
[2] http://www.parks.wa.gov