Diablo Trails Challenge

A Run for Everyone: 5K, 10K, Half Marathon, 50K

Saturday, April 11, 2020

About the Event

Hosted by Brazen Racing, this fundraising run for Save Mount Diablo showcases just a fraction of Diablo’s natural beauty and helps Save Mount Diablo to preserve, defend, and restore more land for you, wildlife, and future generations to enjoy.

Diablo Trails Challenge has a run for everyone, from those hitting the trail for the first time to experienced ultra-runners, with a 5k, 10k, half marathon, and 50k. The 5k, 10k, half marathon, and 50k all begin and end at Castle Rock Recreation Area in Diablo Foothills Regional Park, Walnut Creek. All races are professionally timed. Runners receive medals after the race.

Thanks to all participants, volunteers, park rangers, ham radio volunteers, Contra Costa Sheriff’s search and rescue teams, and sponsors for making this run possible.  

Trail Runner Reviews

The absolute best run I’ve ever participated in was my recent Save Mt. Diablo 10K Trail Run last weekend. There were luxury bus shuttles to Castle Rock Park from Northgate High School and they ran frequently. A wonderful baggage check area was well organized, and they had lots of tents set up to assist people who hadn’t picked up their packets early. The course was beautiful with lots of hills and creek crossings. The drink/aid stations were the best part. They had all sorts of snacks, drinks, candy, treats, and even ice cold water to sponge you off if you wanted! It was amazing!

At the finish, after receiving beautiful medals, delicious It’s-It ice cream was being passed out. I picked pumpkin flavor and enjoyed the sweet treat before waiting in line for some chips, popcorn, fruit, cookies and candy. There was also a plate of BBQ available for $10, but I probably would pass this up next year – the event food was better than the plate I received. Everything about this race was perfect. It was absolutely my favorite event thanks to the great organizers and volunteers. Brazen racing is the best!

Amy Schroll

What makes this a unique trail event are the Search and Rescue volunteers, on-course radio communications and timing chips. Also, it benefits Save Mount Diablo, enabling people to safely explore new, unfamiliar terrain (including new trails, and new off-road courses for people who’ve only run roads in the past). It’s much more of an adventure than any road run you’ll do!

Dave, Danville, CA

I love the concept of going through at least 5 parks-from Round Valley to I believe Los Vaqueros Watershed to Morgan Territory into Mount Diablo State Park and veering into Shell Ridge Open Space before finishing back up at Castle Rock Park. I especially appreciate all who put the event to together and made it happen such as Mike Palmer and the Save Mount Diablo Committee. And a special thanks to those who marked the course-they did a Great Job!-I usually go off the course in almost every 50 K I’ve done-this one I remained on the Course the whole way.


I came for inspiration and self-revelation through a mixed feeling of suffer and grand breathtaking scenery. I felt touched at every steps and every bit of service from the volunteers. Thanks to all who helped make our day!!


I look forward to running the event next year. I will now be able to give more info to my customers about this wonderful event! You all did a great job from start to finish. I am so happy an organization is in place so that we all can have this wonderful mountain to play on.

Roberta McGraw, Forward Motion

You and the Save Diablo volunteers did a super great job putting on the race and introduced many people, including me, to beautiful trails that we never knew existed. The aid people were plentiful and enthusiastic.


Thank you to everyone involved in Sunday’s run. Although I was cursing a little toward the end, a day later I am reflecting back with a very happy and positive feeling. The aid stations were great, the volunteers were even better. All the volunteers had infectious energy all the way through to the end! The hills and views were the best I’ve seen on any course and I had a feeling of pride, running (and completing) the first official Diablo 50K. The course was beautifully challenging (and the wind didn’t make it any easier). 


Race Information

Race Information

For race and course details, please visit Brazen Racing’s website.

Register Here

2018 Race Results and Event Photos

Thanks so much to all of the trail runners who came out to participate in the Diablo Trails Challenge.

We had 1,050 runners this year, and the weather was sunny and warm.

View your race results here.

Hosted by Brazen Racing, proceeds from the Diablo Trails Challenge benefit Save Mount Diablo.

Thanks for your support!