Rainbow Falls State Park State Park includes 139-acres of spectacular scenery along the shoreline of the Chehalis River. Rainbow Falls campground has 53 campsites set among an old growth forest. There are 39 standard sites, 8 RV sites, 3 horse campsites, and 3 hiker/biker only campsites. The campground has one dump station, and one restroom with flush toilets and hot showers. Each campsite has a table, fire ring and grill. Outdoor activities include fishing, hiking, biking, swimming and wildlife viewing.