Boulder Creek Trail leads into the Elwha side of Olympic National Park, where the forest feels deep even before the route gets difficult. It is best known as the access trail toward the Olympic Hot Springs area, though the springs themselves are undeveloped and conditions vary.
The appeal is the combination of river country, big trees, and a quieter backcountry mood than Lake Crescent or Hurricane Ridge. Check current road and trail access before going; washouts and closures in the Elwha valley can change plans quickly.