These train tracks were in use until 1976, when Hurricane Kathleen damaged them. They meander for miles through the arid terrain via tunnels and trestle bridges, including Goat Canyon Trestle, one of the largest wooden trestle bridges in the world. Mountain biking is an option, but beware that it's a rough ride and dangerous in spots. It's easy to see why it was once dubbed the Impossible Railroad. Directions: I-8 east, exit Imperial Highway to Ocotillo, left on S2, then left on Dos Cabezas Road (which requires 4-wheel drive).