Six miles south of Forks [1] on Highway 101, Bogachiel (Native American for Muddy Waters) State Park encompasses 123 acres on the usually clear Bogachiel River. Enjoy the short nature trail through a rain forest, or swim, paddle, or fish in the river—famous for its summer and winter steelhead, salmon, and trout. The park has campsites (360/374-6356, www.parks.wa.gov [2], $13 for tents, $19 for RV hookups) and is open year-round.
Links:
[1] http://www.moon.com/destinations/washington/olympic-peninsula-and-the-coast/olympic-coast-and-hoh-rain-forest/forks
[2] http://www.parks.wa.gov