OverviewEl Centinela (The Sentinel) is an impressive summit rising abruptly from the flat farmlands and deserts along the Mexico-U.S. border. The peak lies within Mexico, its summit about two miles south of the border. On the U.S. side, the peak is called Mount Signal, and is visible from as far away as the Salton Sea. The peak has an impressive profile, despite the fact its summit is just a shade below 2,500 feet above sea level. It is a result of uplifting, lying along the San Andreas Rift Zone. El Centinela has about 2,165 feet of prominence, bearing in mind that most of the surrounding desert flats are at or below sea level.
Centinela seems to be a popular hike for Mexicali-area hikers, potentially busy during winter holidays. Given its location, winter is the only reasonable time to climb the peak. Summer highs can reach above 120 F (over 50 C). A good trail and use-path leads to the summit, but the route includes a few sections of rock scrambling and steep, loose slopes. There is nearly no significant vegetation on the mountain: a few stands of ocotillo are found up high, and creosote dots the hillsides in places. There are small clumpy grasses, but very little cactus, and nothing that provides shade. This is about as stark as a desert summit can get. The views from the summit are superb, including views of distant Picacho del Diablo, way to the south on the Baja Peninsula.
The Mexican military often encamps on the north slopes, literally within yards of the border, while American Border Patrol vehicles can be seen a few hundred yards away. Access is not restricted, but stealthing it across the border is not advised. Day trips are fine. I wouldn't hang out here in the evening.
I was fortunate to climb the peak with Dr. Brian McNeece, a professor at Imperial Valley College and an expert on this part of Mexico. He has climbed the peak 18 times.
There are some Mexicali-based hiking groups that go to the peak. I googled and found a group on Facebook that is based in Mexicali.
Earthquakes are not to be discounted. A big 7-magnitude rumbler hit Mexicali during Easter 2010. We saw evidence of new rockfall up on the peak as we hiked, likely from this shaker. Aftershocks are common.
Generally: From Mexicali, somehow find your way south a couple miles to Mexican Route-2, the main road east-west through town. Head west toward Tijuana. About seven miles from town, with Centinela's lovely profile in view, turn right past a stockyard signed as "Karne". The road is also marked for "bombeos" (pumping plants). Go north on this road about 3 miles to a T-junction. Then go left to a bombeo (pumping plant). You'll see big blue tubes going up the slope to a blue tower. This is part of an aqueduct sending water to Tijuana. Past the pumping plant follow a dirt road around the base of the ridge. You should see a road snaking up the ridge to this big blue tower.
You can park low and walk the road to the tower, or if you trust you 4wd vehicle enough, rumble up this road and park at the small clearing below this tower.
The Mexican military guys were encamped here, but they allowed us to pass, and they seemed friendly.
At some points along the road past the pumping plan t, you'll be within mere feet of the border, marked by low fencing.