Big Cienega Trail begins off the Windy Gap Trail above its second junction with the South Mt. Hawkins Road. From there, it climbs westward above Big Cienega Spring through stately old growth pines and cedars until it reaches the Islip Ridge Trail. From this junction, you can hike one mile to the summit of Mt. Islip, travel to Little Jimmy Campground, continue the loop to Windy Gap or you can hop on the Pacific Crest Trail.
Directions from Azusa, CA: Travel San Gabriel Canyon Road 25 miles north to the Crystal Lake Recreation Area.