Waldo 100K
Willamette Pass, United States • 1 Aug 2026
Waldo 100K Ultramarathon
The Waldo 100K is a 100K loop course held in Oakridge, Oregon, that begins and ends at Willamette Pass Ski Area. The start location sits at elevation 5,120 feet and the course is roughly 70 miles east of Eugene, Oregon.
The route climbs several named mountains, including Fuji, The Twins, and Maiden Peak, before returning to the ski area. The course runs mostly on single track trails and passes through some fairly remote sections. Runners encounter multiple viewpoints along the route that include views of Waldo Lake.
Organizers note that the event is not intended for beginners and is recommended for runners with ultramarathon experience. For 2026 the event used a lottery process for entrants; registration for that lottery included an optional contribution to a Trail to Zero carbon offset program. The Trail to Zero materials cited a statistic from 29 mass participation events between 2014 and 2019 indicating that 98.5 percent of an event's carbon footprint came from participant travel.
Registration for the 2026 event closed January 21, 2026. Visit the organization's website for the most recent information.