Mount Formidable is a mountain in the North Cascades of Skagit County, in Washington state. Its first ascent was undertaken by members of the original Ptarmigan Traverse, and the peak is a popular climb for parties on the traverse.: It was named by early mountaineer Herman Ulrichs in 1935 because of the rugged appearance of its north face.: The peak is usually accessed from Cascade Pass via the Ptarmigan Traverse.