Marin Ultra Challenge Mill Valley, CA   Mar 14, 2026

The Marin Ultra Challenge, Inside Trail Racing’s premier Marin County long distance trail race, delivers ample hills and sweeping descents. Meticulous effort went into the design of each course for the MUC; all three distances are physically demanding (the 50 Mile has just about 11,000 feet of elevation gain) and exceptionally beautiful. The journey begins underneath the Golden Gate Bridge, then traverses the Marin Headlands, Stinson-facing Mt. Tamalpais and Muir Woods, exhibiting a range of terrain, from exposed fire-roads with incredible coastal and inland views to tight, technical single-track with redwood canopies. There is very little trail overlap, and Jim Vernon, from The Endurables and Hydrapak, spent hours and weekends developing these spectacular custom courses – we are super excited to show it off. You’ll quickly realize why Marin County has become the ultimate trail runner’s destination.