The first half mile of trail follows the path of an old pipeline northeast across gently sloping muskegs and scrubby forests. The trail enters the forest and begins climbing the side of Gavan Hill. The Gavan Hill Trail continues up while looping east and north along a low ridge. At an elevation of about 500 feet it begins a series of numerous switchbacks up the southeast flank of Gavan Hill. Upon attaining the Gavan Hill ridge, the trail runs through a forest of stunted trees, which gives way to subalpine meadows after a quarter mile.
Some sections are muddy and steep.
Bears may be present. The road winds 5 miles up Harbor Mountain gaining 2000 feet elevation. This is a steep climb with sharp switchbacks. Recreational vehicles and vehicles towing trailers should not attempt the drive. The road was built during World War II to provide access for building a lookout and other military installations at the top of the mountain.