sr 236 begins with an at-grade intersection with sr 9 within the small town of boulder creek. the road then heads northwestward through an area of evergreen forest, exiting the town. after several switchbacks, the route heads westward into big basin redwoods state park, where its name is big basin highway. amidst the park, the road turns abruptly toward the north, where it continues winding through the forest. as it exits the park, the road abruptly turns eastward again, heading again toward sr 9, where it meets its northern terminus.