421

Trail #421 starts at an unmarked intersection with #400 on a shelfy and narrow section of the trail beneath the pine trees. Right away there is a section of rocky trail with boulders embedded in the surface of the dirt, followed by a rocky creek crossing in an overgrown bushy area. The climb out fro...

When to go: Summer and Fall typically offer the best window.

Vehicles: ATV, Dirt Bike, Jeep/Truck. Standard offroad prep applies: appropriate tires, ground clearance, and a basic recovery kit.

Southwest Idaho context

Southwest Idaho splits across the Snake River. South of the river is Owyhee high desert — sage flats, slickrock canyons, and a million-plus acres of BLM. North is the Boise National Forest, with mining-era roads, ponderosa, and quick out-of-Boise access. Most weekend trips work off Boise, Mountain Home, Marsing, or McCall.

Best for drivers who understand their vehicle and the cost of a mistake in remote country.