Yamsay Mountain is a large shield volcano in south-central Oregon, east of Crater Lake, and one of a distinctive eastern line of Cascade volcanoes set behind the main volcanic front. Formed by the ongoing subduction of the Juan de Fuca Plate beneath North America, it rises higher than nearby Newberry and Medicine Lake volcanoes and reflects the region’s varied volcanic history. The mountain also holds deep cultural importance: its name comes from Klamath Yamsi, linked to “north wind,” and in Klamath mythology it was the home of Kmukamtch, while the Northern Paiute called it paba katɨdɨ, “big sitter.” Later, the area saw trapping, settlement, and a Forest Service fire lookout, whose old road now serves hikers.