Fodor's Expert Review Firehole Canyon Drive

The 2-mile narrow asphalt road twists through a deep canyon of curving lava-rock formations and passes the 40-foot Firehole Falls, which are most scenic in the morning when you're not looking into the afternoon sun. In summer look for a sign marking a pull-out and swimming hole. This is one of only two places in the park (Boiling River on the North Entrance Road is the other) where you can safely and legally swim in the thermally heated waters. Look for osprey and other raptors.