The Ohlone Wilderness Trail is a 28 mile one-way trail that connects Del Valle Regional Park (just south
of Livermore, CA) to Mission Peak Regional Preserve (in Fremont, CA). It passes
through Ohlone Regional Wilderness and Sunol Regional Wilderness, as
well as some land owned by the San Francisco Water District where you’re
not allowed to leave the trail.
The trail is 28 miles in length, not including short detours to campsites or to the top of Mission Peak. There are many out-and-back options for hiking in this area.
A shuttle or other transportation arrangement is required to thru-hike the entire 28 miles.
For more trip details, check out this NorCal Hiker blogpost.