This 12 mile out and back starts at the same trail head as the Iceberg Lake Trail by the Swiftcurrent Motor Lodge in the Many Glacier area of Glacier National Park. The Ptarmigan tunnel trail and the Iceberg Lake trail share the first 2.8 miles of trail. At that point, Ptarmigan splits to the right and Iceberg continues straight. The grade is relatively steep after you branch off from the main trail but the trail is very well maintained. You reach Ptarmigan lake and can then see the wall of switchbacks up to the tunnel. Be sure to walk at least 1/4 on the other side of the tunnel to get views of Old Sun Glacier as shown in the video. Enjoy the trails!