The Waldo 100K Ultramarathon is a challenging 100K loop-type course starting at Willamette Pass Ski Area (70 miles east of Eugene, Oregon) at elevation 5120′, climbing up several mountains including Fuji, The Twins, and Maiden Peak before returning to the ski area.

The route is mostly single-track trails with some fairly remote sections and has many incredible views of pristine Waldo Lake. It is not a beginner-level ultra and participation in the race should not be taken lightly.