Mount Mystery is one of the prominent summits of Washington’s eastern Olympic Mountains, rising 7,639 feet within Olympic National Park and ranking as the range’s sixth-highest peak. South of Mount Deception, it stands above the divide between the Dungeness and Dosewallips basins, with Deception Creek draining both slopes and a small east-side glacier known as Mystery Glacier. Named about 1915 by G.A. Whitehead of the U.S. Forest Service for its regal look in fog, the mountain lies in the Olympic rain shadow and is drier than the wetter western Olympics. Formed from oceanic crust and sedimentary material, it was later shaped by glaciation and erosion.