On a map the roads show as thin red lines forming a network resembling blood vessels and capillaries. Or the tributaries to a river. Between Swan Falls Dam and Celebration Park on the south side of the river there is a gap with no red lines. Since a few of the dozen or so other riders here have ridden this route before we know there is a way through.
Crossing over Swan Falls Dam we head upriver a few hundred yards before taking a sharp right hand turn to reverse direction and begin climbing. The surface is generally gravel and/or sand but on a few of the steeper sections larger boulders are exposed and overlain with other, melon sized boulders. These sections most of us walk while pushing the bikes. Then the road smooths out and descends again toward the river. It is nice, fast double track here.
The road-less gap on the map is an area where the canyon walls slope rapidly down to the river. The trail winds up and down and through vehicle sized boulders and the trees and brush that grow along the river. Here everyone pushes and carries their bikes. Then the trail drops steeply back down to the river and ties back into a gravel road which we follow all the way to Guffey Bridge which crosses the river to Celebration State Park. We have ridden about 12 miles at this point. The trail on the north side of the river from Celebration Park back to the dam is mostly level with some sections of deep, loose sand and some rocky sections. Riders with 3″ wide or wider tires should be able to ride everything without much trouble.
This loop is just about 25 miles and it is less than an hour’s drive from Boise so it makes an easy day trip. We stopped often to tour through the old stone buildings and to look at petroglyphs. The visitor center at Celebration Park is a resource to learn about the geology and history of this country and is worth a stop.