Corteo Peak is an 8,107-foot mountain in Washington’s North Cascades, just west of Rainy Pass on the eastern edge of North Cascades National Park. Its summit rises sharply above nearby Maple Creek and Lewis Lake, and its north side holds remnants of the retreating Lewis Glacier. The peak stands within a marine west coast climate shaped by Pacific storms, bringing heavy winter snow, avalanche danger, and clearer summers. Its name reflects a small human history: Forest Service surveyor Lage Wernstedt named it, and nearby Mount Benzarino, for Basque sheepherders he met here. The surrounding rugged landscape was formed over millions of years by terranes, uplift, faulting, and repeated glaciation.