Threemile Trail has a total elevation difference of 2,546 feet which is higher than average. Of course, this is an overnight backcountry hike, 1.5 days normally, so it's a wonderful thing if your backpack is big enough to do the job. Different parts of Threemile Trail are at very different elevations, so keep in mind that you may need to dress differently at different elevations. Threemile Trail is quite long, so make sure you bring plenty of supplies. Threemile Trail is 11.2 miles long; it's considered a longer trek. Threemile Trail has only one trailhead, so you're looking at an in and out backcountry trek.