Quien Sabe Glacier occupies the west slopes of Boston Peak in Washington's North Cascades National Park, where it sits among closely packed glaciers divided by sharp ridges and steep mountain walls. About 0.60 mile long and roughly 0.70 mile wide at its terminus, it descends from about 8,400 feet to 7,200 feet. Its history mirrors broader glacier change in the North Cascades: from its Little Ice Age maximum around 1850 to 1950 it retreated about 1,200 meters, then advanced 55 meters between 1955 and 1975, before retreating another 200 meters by 2010. These measured shifts make it a clear indicator of long-term environmental change.