From the Tooth Rock Trailhead, start by walking east on the paved Historic Columbia River Highway Trail. After 2/10 of a mile, you'll come to a junction with a trail going up to the right marked by a sign that says "Tanner Butte Trail." Start up the hill for another 4/10 of a mile until the trail splits. Follow the trail to the right. At this junction is a sign marked "Trail 400/Wauna Pt/Tanner Butte Tr."

Head up this steep trail for roughly 100 feet to Tanner Creek Road. This is a 4-way junction. Look for a sign that says "Gorge Trail 400" with arrows pointing left and right. Follow the trail (which is as wide as a road and goes uphill) to the right. When this road splits, bear left (the road on the right will have two signs marking it trail #400 and 034). After that, you will cross several service roads. Continue straight on the road you're on (Road 777) until you reach the old Tanner Butte Trail #401 trailhead.