The Slot at Anza-Borrego

The Slot is a 2-mile narrow-walled sandstone canyon in California's largest state park, navigable on foot during the winter dry-season (October through April) and unsafe to attempt during the late-summer monsoon flash-flood window. Walls narrow to roughly shoulder-width in the middle quarter and the trail involves stemming over chockstones and ducking under wedged boulders. The trailhead off Buttes Pass Road is a dirt-and-sand pullout with maybe 15 cars worth of space; RVs explicitly cannot drive Buttes Pass Road past the first mile due to deep sand. Rigs stage at Borrego Palm Canyon Campground (35-ft cap, full hookups including 50-amp service — rare in California state parks), 8 miles east in Borrego Springs. The slot's signature inverted-arch chockstone bridge at mile 0.8 is the most-photographed feature; the canyon dead-ends at a sheer pour-off another half mile beyond it.