San Gorgonio is Southern California's tallest mountain, and its 11,500-foot summit stands tall among the San Bernardino Mountains east of Los Angeles and north of Orange County. When compared with ascents up San Bernardino, Mount Baldy, or San Jacinto Peak, the trail to the summit is actually pretty long, but the views from "Old Greyback" will help distract you from the long 8.9-mile route to the summit. This approach can be completed as a long day hike or a multi-day adventure; there are a couple of campsites along the way. As always, remember to follow Leave No Trace practices when you are in the backcountry.
Start the Vivian Creek approach by crossing Mill Creek, which should be dry in the summer but is occasionally flooded with water. The trail begins climbing in earnest once it crosses the creek, proceeding through switchbacks to rise almost 1,000 feet in just over a mile. The scenery changes after the switchbacks and approach the Vivian Creek Camp, where there is more water and foliage. You'll find abundant wildflowers in the summer and gorgeous leaves in the fall. The campsites sit at 7,100 feet and are located to the right of the trail after it reaches the stream. The first camp is halfway up the slope, and the other is at the top of the slope. Remember that there is no camping within 200 feet of the trail or creek.
This will be your first chance to fill up your water; the next reliable water source is 3.6 miles away at High Creek. You'll pass a forest covered with manzanita and Halfway Camp before following the switchback toward the southern ridge of San Gorgonio Mountain. As you climb in elevation the vegetation transitions to lodgepole pines and white fir. Look for glimpses of Mount Baldy through openings in the trees. You'll arrive at High Creek after climbing through some additional switchbacks, and this is another opportunity to camp or rest before pushing on toward the summit.
You'll reach the beginning of the ridge after 6.5 miles of grueling trail. San Jacinto stands impressively to the east, but there is still a long way to the summit. The trees start thinning, and soon you will be above the tree line. Keep following the faded trail and you will reach the junction with the San Bernardino Peak Divide Trail (that can be accessed from the Momyer Trailhead).
The real summit is still hidden behind the ridge. Keep going and you will see the summit, where you can enjoy the amazing 360-degree views. There are some rock formations that will give you shelter if the wind is blowing hard. This rock shelter can also be handy if you decide to camp on the summit overnight, but keep in mind that even when it's really hot in the valley, the temperature at the summit can get pretty cold during the night.
Permits can be booked ahead of time by faxing an application. Unfortunately, applications can't be sent online or by email. There are also three walk-in permits available everyday. Make sure you plan ahead as the hike is usually fully booked a couple of weeks in advance. Also, the office is closed on Tuesday and Wednesday every week.