Annadel Half Marathon, 10K & 5K Santa Rosa, CA   Apr 18, 2026

The Annadel Half Marathon is a non-profit fundraising event. Over the past decade+, we have raised funds to make the park a more beautiful place for all to enjoy! Thankfully with the help of our sponsors, race participants, and volunteers this is a very successful event. The Annadel Half Marathon, 10K, and 5K are considered to be one of the biggest running events in Sonoma County!

The Half Marathon course is a hilly, and technical course designed for the experienced trail runner looking for a challenge. Enjoy gorgeous scenery with green meadows, wild flowers, and variety of beautiful trees. The race starts near the Upper Oak Knolls picnic area and climbs into Annadel State Park. The Annadel Half Marathon is a tough course with wet, rocky and rooted terrain. The race will feature chip timing, a free t-shirt, a finisher medal, post-race food and beer!

The Annadel 10K is a tough course with wet, rocky and rooted terrain. The race starts near the Upper Oak Knolls picnic area and climbs into Annadel State Park. Elevation gain for the race is approximately 631 feet.

The 5K course is a hilly out and back course. The race starts near the Upper Oak Knolls picnic area and climbs into Annadel State Park.