4800 feet gain
Drive north on the 243 from Idyllwild a few miles to the San Jacinto State Park Entrance. Turn right and follow the signs for Marion Mountain Campground.
Drive south on the 243 from Banning 19 miles to the turnout for San Jacinto State Park. Turn left and follow the signs for Marion Mountain Campground.
Park at the locked gate, follow the road to the trail, or continue on the road to the campground where you can also begin the trail. Follow this trail to the PCT, turn left, and follow the PCT until it intersects with the Fuller Ridge Trail, stay right and ascend the Deer Springs Trail past Little Round Valley to the intersection of the Peak Trail. Clamber up the rocks to the summit.
Even though I have never seen a ranger on any trail in Southern California, you need to get a permit to enter the San Jacinto Wilderness. Get it from the station in Idyllwild.
This trail is a butt-blaster. It feels longer than it is, it takes longer than suggested, and it will make you work for your summit the entire way. This is the shortest route to San Jacinto without cheating, but it is by no means the easiest.
You get it all - the range of San Jacinto plant life, great views and a killer workout, however the way down is almost as bad as up. I rate this a ten on the toejam scale. It feels like 18 miles not 12. Even my usual stellar 3.2 mph trail average slipped to a dismal 2.3 mph on this one.
It is a tough go, and I will probably never take this trail again, although the views are worth it - I'll take Fuller Ridge or better yet - cheat. Palm Springs Aerial Tramway is kind of cheap.