The Terrell Marsh Trail weaves a 0.5-mile loop through the forested eastern portion of Birch Bay State Park, and it is accessible from near the campground entrance. Although the area was logged with oxen and horse teams during the early 1900s, many large trees have re-established themselves over the past century. Several interpretive signs guide you along the well-maintained, level path. Thick groundcover and understory foliage create a lush green environment in the mixed forest of western red cedar, paper birch, red alderwood, black cottonwood, hemlock, and Douglas fir. After a quarter mile, a small spur trail leads to a bench and viewpoint of Terrell Marsh, which is one of the few remaining brackish estuaries in the north Puget Sound. The trail is for hiking traffic only, and there is a bike rack near the trailhead.