This hike climbs to Carey's Castle, a mining ruin on the south edge of Joshua Tree National Park. You start off up an alluvial slope with scrub and cactus, then work your way up a twisting canyon with yucca, boulders and scrambling. The "castle" is a small dwelling near a mine shaft at the upper end of the canyon. There's no trail, which can be fun if you like exploring. It's best to use GPS to navigate several unmarked forks in the canyon. Please avoid disturbing the historical site around the castle.
open accessyear-roundany vehicle
The final approach to the trailhead is along unnamed dirt roads. These are usually suitable for highway vehicles and fairly easy to follow. However some mapping apps may not have good coverage in the area and may have trouble providing detailed driving directions.
Exit I-10 at Chiriaco Summit and head north off the interstate on Summit Road. Turn right (east) on Chiriaco Road. Almost immediately you'll pass a large parking lot for the Patton Museum on the left. Just past this lot, before you reach the Chevron station, turn left and head north on an unnamed road that soon turns to dirt. When you reach a T-junction after a couple minutes, turn right and follow a 2nd unnamed dirt road all the way to the unmarked trailhead.
The hike itself is technically within the bounds of Joshua Tree National Park, so park rules concerning historical sites and environmental protection do apply. However due to the remote location there's no obligation (or opportunity) to pay an entrance fee.