Thursday, December 19, 2013

San Ysidro Mountain, The Thimble, White BM, Bonny BM

Hiked: 12/18/2013
Distance: 9.4 miles round trip cross country and use trail
Summit Elevation: 6147' (San Ysidro), 5779' (Thimble), 5326' (White), 4574' (Bonny)
Prominence: 947' (San Ysidro)
Elevation Gain: 3248' (combined)
Elevation Gain (in Empire State Buildings): 2.59
Round trip time: 7 hours 30 minutes
Recommended water: 128 oz.
Parking/Fees: Free on the side of S22 (Montezuma Valley Road)
Difficulty: Strenuous

San Ysidro is on the Sierra Club Hundred Peaks list and also the San Diego County Peaks list. It is also one of the highest in the Anza-Borrego Desert State Park. I had climbed one other nearby desert peak, Indianhead, and it was tough, so I expected a difficult cross country, cactus filled day. I wanted to hike Ysidro before Thanksgiving, but delayed the attempt due to weather. In mid-December, I wanted to find a nice, snowy hike to break in some new equipment, but two weeks of sun left patchy snow in the local mountains so I went back to Ysidro. Sometimes, you have to take what the weather gives you.

I truly love the desert. Many desert peaks have no trails and everything on the itinerary today was cross country, leaving from the side of Montezuma Valley Road just inside the Anza-Borrego Park. You go past the park sign to the top of the rise, over a cattle guard, then U turn to park on the north side of the road. Day hikes in Anza-Borrego require a serious effort on my part, starting with a 2 hour drive from south OC. I left home at 4:30 AM in order to start at sunrise. I had no trouble getting to the roadside trailhead, with very little traffic in the dead of night. I started at daybreak. The sun rose but I never saw it. It was hidden behind high clouds all day. I started by following the barbed wire fence that separates the park from private land. The brush was not too dense at the start and route finding was not an immediate problem.


Typical terrain in the early going

Constant cactus companions

As suggested in several trip reports, I approached White BM from the west. It was steep, but relatively clear. The summit block was an easy climb and I was glad to get the first one under my belt. I took a shot of Hellhole Canyon off to the east. According to Jerry Schad in Afoot and Afield in San Diego County, Hellhole Canyon earned the name because cattle often wandered into the canyon and it was "hellish" to get them out. A herd of feral cattle apparently lived in the canyon until they were helicoptered out in the late 1980s. After a short rest, I descended back to the west and traversed north toward The Thimble. The boulder hopping and bushwhacking got unpleasant on the northwest slope. I think the east side would have been better.

Approach to White BM

White benchmark

San Ysidro and The Thimble from White

Hellhole Canyon from White, Webo BM on the left

The Thimble looked intimidating as I got near. I ducked through a barbed wire fence (on private property) to take the most direct path. I had heard dogs barking earlier and hoped that they would stay in the distance. I headed directly up the south slope of The Thimble, all class 2 until the last 100 feet. I slipped on a slab and grabbed a nearby bush to stop myself, but the bush bit back, causing a nice blood flow from my left index finger. I had just taken off my gloves as the day warmed up, but after a bandaid, the gloves went back on. Finally, I got to a wall of cliffs and boulders. There appeared to be several tough class 3 routes, but I headed west until I found the chimney that is supposed to be the normal route. There is one chimney behind a tree, but after a close look, I decided to climb another chimney left of it. After that climb, I found a long granite slab with class 2 access to make it the rest of the way. The exposure was not severe in either case, and it was good granite. Once on top, I signed the summit register, took photos, then ate and explored the cool rock formations on the large summit area. The north side looked uninviting for a down climb, so I went down the way I came up, which was easier than expected, then traversed east up a saddle between the The Thimble and another rock ridge. Getting to the wash at the base of San Ysidro was another unpleasant boulder and bushwhacking affair. It was overgrown with buckthorn and not much in the way of animal trails.

Approaching The Thimble

Class 3 chimney

Final slab climb to the top

Summit register on The Thimble

Standing on The Thimble

San Ysidro from The Thimble

San Ysidro Mountain ridge line

Once in the wash, I found cairns leading the way up a reasonable use trail. It was steep, but didn't require any use of hands. For some reason, I was sapped of energy. I think I had been focusing so much on The Thimble, that once it was done, I lost some drive. It took me a lot longer than planned to get up San Ysidro. I forced myself up, only to be greeted by strong, cold winds and thicker clouds. I climbed up to the triangulation benchmark, which is where the summit register was, signed it, took a few photos and started down without wasting time.

Heading to the saddle between The Thimble and rock ridge

The Thimble and White from San Ysidro

San Ysidro benchmark

At this point, I was in no mood for the two boulder/bushwhacks that awaited me on the north slopes of the The Thimble and White. I followed the cairns down to the wash and continued following it west, even though it would take me a mile or so out of the way. I had forgotten what it was like to hike without obstacles. Very nice. I made great time bypassing The Thimble and the worst of White. Unfortunately, it took me back on private land. When I spotted a house, I took a hard left and climbed back near White, then continued on toward Bonny BM.

Bonny was hard to identify. There are many small bumps on the landscape, and I climbed one thinking it was Bonny but it wasn't. It was further back near the road. Again, following the advice of trip reports, I approached Bonny from the east. From the east, there are a couple of obvious class 3 routes, and one class 2 on the left that circles around the summit boulders clockwise. I took the easier way. Bonny is a small peak, with the benchmark and register together in about a six foot wide bowl shaped notch. I signed it and found the entry for Michael Sullivan, whose GPS track I was (sorta) following. I spotted another benchmark on the next boulder, and it was also a triangulation marker, but without the peak name. Very odd. My return to the car led me into more brush but I eventually emerged about 100 yards from my car. I saw a lot of rabbits on the trip but not another human. It was a long, hard day, and a gratifying drive home.

Following the wash back

Bonny summit blocks viewed from the east

The easy way to the Bonny summit

Bonny benchmark

Looking back at White, The Thimble, and San Ysidro from Bonny BM

Thanks to Derek Loranger of for his great trip report that helped in planning, and Michael Sullivan for the GPS track.


  1. Glad to see that you made it out in one piece. I totally understand feeling a little sapped after the Thimble. I think it's likely mental fatigue at not having a nice trail compounded with some of the higher elevation in San Diego.

    1. Hey, Derek. It was pretty tough getting up Ysidro. You are right about the mental energy combined with constant route finding in certain parts. I did get a second wind on the way back and finished off Bonny, and your tip on approaching from the east made it a lot easier. I wish I lived closer to Anza-Borrego. So many great mountains there.