Surprise Mountain is a 6,330-foot peak in Washington’s Alpine Lakes Wilderness, above Glacier Lake in the Wenatchee Mountains and within Mount Baker-Snoqualmie National Forest. Runoff from its slopes reaches the Skykomish River through Surprise and Deception creeks, and the Pacific Crest Trail passes nearby through Surprise Gap. Surrounded by peaks such as Thunder Mountain and Terrace Mountain, it stands in a landscape shaped by volcanic mountain building, the assembly of crustal terranes, and repeated Pleistocene glaciation, which carved the region’s deep valleys and stark relief. Its western Cascade marine climate brings heavy rain, abundant winter snow, avalanche danger, and generally clearer summers.