Mount Formidable stands in Washington’s North Cascades on a spur ridge west of the Cascade crest between Cascade Pass and Dome Peak, near Spider Mountain and along the Ptarmigan Traverse. Named in 1935 by mountaineer Herman Ulrichs for the rugged appearance of its north face, it was first climbed by members of the original Ptarmigan Traverse party, tying it to the region’s exploratory climbing history. Its north side holds the Middle Cascade Glacier, whose meltwater reaches the Skagit River through the Cascade River. The mountain’s remote, severe setting is shaped by heavy snowfall, temperate rainforest conditions at lower elevations, and rocks including granitic formations, schist, and metamorphosed Triassic igneous rock.