Mt. Whitney, Franks Peak, Double Peak, San Marcos Peak, Cerro de las Posas

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September 1, 2016
Just south of San Marcos in north San Diego County are a small cluster of urban hills under 2,000 ft of elevation, the highest of which is a P1K called Mt. Whitney. I had first noticed it while casually scanning local topos, also noting several other hills nearby. I decided to save these hills for a foggy morning in September, hoping to catch a sunrise above the fog.

PeakElevationTopographic ProminenceSummit Coordinates (lat/lon)
Mt. Whitney1,736 ft1,046 ft33.1089, -117.1553
Franks Peak1,688 ft238 ft33.1050, -117.1572
Double Peak1,644 ft474 ft33.1094, -117.1777
San Marcos Peak1,220 ft40 ft33.1114, -117.2022
Cerro de las Posas1,350 ft180 ft33.1082, -117.1928

Getting to the trailhead (Double/San Marcos/Cerro de las Posas)

Trailhead coordinates (Whitney/Franks): 33.1101, -117.1542

Trailhead coordinates (Double/San Marcos/Cerro de las Posas): 33.1248, -117.1788

Mt. Whitney and Frank's Peak are located on the east side of their hilly cluster. They seemed to be popular with local joggers who frequently used the area for workouts. I arrived at my starting point at around 5:40am as the eastern horizon was beginning to brighten up, parking at the last public access point before a gate on Washingtonia Dr, right across from the start of a long driveway to a distant luxury home. Next to the gate was a sign indicating "authorized personnel only." No one else I previously talked to had had any problems here, so I authorized myself and continued up. From there, it was a few minutes walk along a paved road to the summit of Whitney, which was crowned with a large transmission tower. I enjoyed some nice dawn scenery from the summit of Whitney, then headed off southwest for a short walk along connecting trails to the summit of Franks Peak where I watched the sunrise. I noticed Double Peak to the west just barely poking out of the fog. That was to be my next destination.

summit of Whitney

summit of Franks Peak

back at the start

I got back to the car at 6:50am and drove over to Lakeview Park in San Marcos. Based on what some friends had told me, it was a popular local workout to hike up Double Peak from this park.

Lakeview Park

I started off by walking up a main road heading south out of the park, passing by the west side of the tiny Discovery Lake. This road (or fancy trail) continued south up a hillside, through a residential area, and up another hillside.

Discovery Lake

fancy trail

As the fancy trail reached a large junction above the residential area, I turned right, walked about a hundred feet, and located a use-trail heading south. This would lead to the summit of Double Peak, where I popped out of the fog right below its summit. Double Peak's summit was crowned with several picnic tables and a telescope. The most interesting thing (at least in my opinion) was a diagram indicating nearby landmarks, including Mt. Whitney, Franks Peak, and San Marcos Peak.

From Double Peak, I took the Ridgeline Trail west along the broad ridge connecting Double Peak to San Marcos Peak. The total distance between these two peaks was about 1.5 miles and consisted of the same type of well graded fancy trail that was found north of Double Peak.

San Marcos Peak's highpoint was crowned with a series of radio towers.

I hit the highpoint of Cerro de las Posas on the way back from San Marcos Peak, taking a side trail that branched off the Ridgeline Trail just west of Pearl Dr. I walked a few hundred feet on this side trail, turning west (right) upon noticing a fence ahead, walking about 100 ft to the highpoint which was pretty uninspiring.

I headed back along the Ridgeline Trail, eventually intersecting the trail I had used to ascend Double Peak, taking it down to Lakeview Park. Everywhere along the trail were locals out for their morning workouts- quite a nice way to spend a Thursday morning.

Stats for Whitney/Franks
2.4 miles
800 ft gain/loss

Stats for Double/San Marcos/Cerro de las Posas
6.9 miles
1,840 ft gain/loss

Weather Forecasts
all peaks

Peakbagger Pages
Mt. Whitney
Franks Peak
Double Peak
San Marcos Peak
Cerro de las Posas

Summitpost Pages
Double Peak


  1. i don't know if this is a repeat comment, it seems my internet might not be working, but really waht i would like to know is how to scale/hike mt. whitney because the way you described, getting up to some gate with nothing more than a "not authorized" sign is not there anymore. when we went up there this last Sunday, there was a three-way culdesac and all of them remarked about private property and the one that we thought might lead up to the summit had a sign that said something like 'restricted access' and 'police will be notified,' and if that wasn't bad enough, there was a camera set up. so i guess what i'm wondering is if this was the same set up you encountered and if there is some other way to access mount whitney. btw we also tried from twin oaks valley and that did not work; there was a winery and a fence and some sorely looking gargoyles...

    1. That was not the case when I was there- just the gate with the not authorized sign. I imagine there would be another way to approach it from the south. There were lots of bike tire tracks around the saddle between Whitney and Franks.

    2. check it out again. i think they changed some things. i was really excited about your trails but it looks like they have been wiped out. we took the trail from san marcos peak to double peak, it's still good. but mount whitney now seems completely inaccessible for hikers. i would welcome a suggestion of a new trail.

    3. That's the way, tho. People do go around that gate (and camera set up) all the time, including the guided hikes organized by the city (there's one coming up in November: ). I don't think the camera is monitored (it just takes footage in case something happens up there).

      The winery route (Bella Vita Way) is private indeed (tho there's really that one gate. Just a chip shot beyond it is the intersection with Atterbury). If you're hiking, tho, you can try coming up Atterbury from Questhaven (it turns into moderately gnarly dirt with lots of pebbles for a stretch after the school, but becomes paved again before it links up with the top of Bella Vita Way and on to Washingtonia.

  2. Lilah I own the 10 acres on the north side of the Whitney peak. The gate is on my property. If u hike up the asphalt you are always welcome. It's a beautiful view from the top. Eventually I will gate the road at the bottom but only to stop vehicles - I welcome hikers and bikers because they don't litter and party up there.


    1. It sure is beautiful and mellow up there. Thank you, Sam!

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