Seaborg and Mariposa Loop Trail is a 9 mile lightly trafficked loop trail located near Orinda, CA that features beautiful wild flowers and is rated as moderate. The trail offers a number of activity options and is accessible year-round. Dogs are also able to use this trail.
I took the Seaborg Trail and hiked up to the Crescent Ridge Trail and back. For a total of 3.8 miles I finished in little more than an hour. Got some good workout with some fantastic sunset view on the way.
Longer loop that is less traveled than most of the trails on the Reliz Valley Rd side. A good cardio and a good place to put some miles on with less people