The views to the south from the summit of Mt Islip are nothing short of stunning. You can see Crystal Lake, the front range of the San Gabriels, as well as the San Gabriel river canyon. I had my lunch looking at this vista and felt like I was in heaven. The hike starts out heading up a forest service road for a half mile, then you head left at the signed trailhead to Little Jimmy Camp, one mile ahead. I really like the gently rolling, pine shaded trail into Little Jimmy Camp. The less ambitious in your group can relax in the camp (it has rest rooms and a spring a 1/4 mile away), while the balance of your group heads up to the summit.
The summit trail is at the back of Little Jimmy camp (walk past both rest rooms). The summit trail takes you up some switch backs to a ridge line. There is a junction with another trail at the ridge line that comes up from Crystal Lake, but you should stay on the ridge line trail up to the summit.
TO TRAILHEAD: Follow Highway 39 twenty-five miles from Azusa to the Crystal Lake Recreation Area. You may leave your vehicle in the dirt parking lot in the upper part of the campground. A National Forest Adventure Pass is required for your vehicle while parked in this area unless you have paid to enter the Crystal Lake Recreation Area.