Discover the beauty of Mount Diablo and support the cause of Save Mount Diablo!

Update: Online registration will remain open until 6:00 pm on 4/18. Race day registration will be open, starting at 5:45 am (for the 50K) and 7:30 am (for half marathon, 10K and 5K distances).

For over 40 years, Save Mount Diablo has worked tirelessly to preserve and increase the open space on and around Mount Diablo. In that time, their efforts have taken us from 6,788 acres of open space to over 100,000 acres of open space on and around the mountain!

With distances suitable for everyone from those hitting the trails for the first time to experienced ultra-runners, the Diablo Trails Challenge was created to help celebrate and support these achievements. A portion of all entry fees will go to Save Mount Diablo to help them continue preserving open space and trails for all of us to enjoy.

All runners will receive custom finisher medals and custom shirts (cotton and tech shirts available). More info on shirts/awards page.

As with all events put on by Brazen Racing, you'll find an atmosphere of camaraderie and encouragement no matter what your fitness level. Walkers/hikers are always welcome (50K will have a time limit but all other courses will be open long enough to accomodate walkers).

Age group awards will be awarded to the top 3 finishers in 5 year categories (smaller categories for the younger ages).

All races begin and end at Castle Rock Park in Walnut Creek.

Start times will be: 6:30 am for the 50K, 8:30 am for the Half Marathon, 9:00 am for the 10K and 9:30 am for the 5K.

All races will be professionally timed with chip timing.

Shirt sizes (and tech shirts) can only be guaranteed to those who sign up by March 29th, so we recommend early registration!


Want to run with us, but can't make it in person?