Rio Del Lago 100 Mile + 50K Endurance Runs

The Jewel of the Sierra Nevada November 7-8, 2026 Welcome to the 2026 Rio Del Lago Endurance Runs Presented by Altra! 🎉 Celebrating 25 Years of the Rio 100 & 5 Years of the Rio 50K! The celebration is on! The Rio Del Lago Endurance Runs presented by Altra return on November 7, 2026, marking the 25th anniversary of the legendary Rio 100 Mile Endurance Run and the 5th running of the fan-favorite Rio 50K. Whether this is your first Rio or your twenty-fifth, we’re doing cartwheels to welcome you to this milestone year. Together, we’ll honor a quarter century of endurance, community, and trail magic on one of Northern California’s most iconic courses