Koppen Mountain marks my last of the Mountaineers Teanaway 20 peaks. Starting from the Boulder DeRoux trailhead, cross the bridge and get to the first trail junction. Take the Middle Fork Teanaway Trail and follow it all the way to to the pass. Make a left at the pass and start traversing southeasterly on the northwest ridge of Koppen.
A hiker’s path is present though occasionally faint. Once higher up the trail becomes much more apparent, follow it all the way to the summit.