Boulder River, a favorite beginner backpack destination in the North Cascades is 4.3 miles (one way) with 700 feet of elevation gain. A few campsites line the trail, however hiking the total 4ish miles to the end of the trail brings you to a nice campsite. Here you can safely jump in the water and cool off in the summer. This trail features a beautiful double waterfall and close up views of the Boulder River.