Perimeter Loop Hike

HARD 3 reviews

Perimeter Loop Hike is a 23.9 mile loop trail located near Mount Hamilton, California that features a lake. The trail is rated as difficult and primarily used for hiking, walking, and trail running. Dogs are also able to use this trail but must be kept on leash.

23.9 miles
4,665 feet

dogs on leash


trail running




wild flowers


This loop hike across parallel ridges of Joseph D. Grant County Park offers sweeping views of the wild, mountainous terrain nearby and occasionally looks out over the southern end of Silicon Valley to the west. You'll see the usual Grant County Park attractions -- wildflowers in spring, tarantulas in the fall, raptors and coyotes all year -- while joining the elite few who have finished one of the Bay Area's most strenuous hikes. Best done in winter when the weather's cool but the trails aren't muddy (provided you can hike this many miles before sunset). Next-best time is spring, when the hills are green and the wildflowers are out. It's too hot in summer, and probably not worth risking in fall if you can't carry enough water for the entire day. This route goes to Antler Point, highest in the park; climbs Washburn trail, steepest in the park; and follows a long stretch of the Bay Area Ridge Trail, which has some of the best views.

8 months ago

Cattle can be out in more than one section. I walked about 2 miles sometimes really close to anxious cows and it didn't feel good. I can't imagine dogs would help such a situation, leash or not.
I started from twin gates trailhead (no water, but there's a porta potty), that way it's a loop without repetition (don't have to go back to the main parking lot) and a bit less than 23 miles.
Pretty good hike, mostly serious up and down, level is less than half.

11 months ago

Very little shade so will revisit and review during a cooler day.

5 months ago