River Of No Return Endurance Runs

River of No Return Endurance Runs - Challis, Idaho, June 20, 2026

The River of No Return Endurance Runs take place in and around Challis, Idaho, with a start and finish at Challis City Park for most distances and a Bayhorse start for the 32K. The event offers mountain trail courses that pass through high terrain, historic mining areas, and sections along the Salmon River. Wildlife sightings reported include elk, deer, eagles, bears and wolves.

Distances offered:

• 108K - about 17,600' elevation gain and 9 aid stations.
• 55K - about 8,800' elevation gain and 5 aid stations.
• 32K - about 4,500' elevation gain, point-to-point from Bayhorse.

Course surfaces include two-track ATV trails, single-track trails, dirt roads and a few miles of pavement approaching Challis. The 108K is a large single-loop with multiple major climbs cresting near 8,000', 9,000' and 10,000'. The 55K follows a lollipop-type route that links to the 32K trails for the finish. The final mile for all races enters Main Street in Challis and returns to Challis City Park; crews and fans may accompany runners on that final section.

Support is crew-friendly for the 55K and 108K with multiple crew-accessible aid stations and scenic access along the Salmon River. The 32K does not allow crew support. Refunds follow a tiered schedule with deadlines in May and June. The race is part of the Idaho Trail Ultra Series. Visit the organization's website for the most recent information.