El Prieto
A frequently trafficked, intermediate level hike in a lush arroyo in the Altadena foothills behind JPL, done as a 9.3km (5.8mi) out & back or can be extended to a 12.8km (8mi) loop hike.
With an elevation gain of 277m (912ft) it’s an inviting hike for beginners to step into the intermediate levels.