Bad Bass - Castro Valley

Bad Bass is an annual running event held at Lake Chabot Marina in Castro Valley, California. Scheduled for July 19, 2025, it offers three race distances: a 5K, 10K, and a half marathon. The event features a scenic course with a paved 5K and trail routes for the 10K and half marathon, showcasing the natural beauty of the Lake Chabot area.

Known for its fun and quirky mascot—a kilt-wearing, bagpipe-playing Scottish bass—the race combines a festive atmosphere with challenging terrain. Participants enjoy well-organized races supported by local sponsors, with opportunities for volunteers and a strong community vibe. Visit the organization's website for the most recent information.