The Boulder River trail is beautiful, with views of waterfalls cascading into the river from the steep banks opposite the trail. It is a relatively easy, popular trail off the Mountain Loop Highway, although you will likely have it to yourself for a quiet trail run mid-week. It starts as a wide, flat path, once an old railroad logging grade, and continues past the Boulder River Wilderness sign, where the river comes into view. You'll encounter a beautiful double unnamed waterfall and old-growth trees along the way with nice switchbacks. Although there are no mountain views, the forest scenery is still captivating.