Siyeh Glacier is a very small ice body in Glacier National Park, tucked into a deep cirque on the north side of Mount Siyeh at roughly 6,800 to 7,200 feet above sea level. Although it bears the name glacier, it now covers less than 10 acres, far below the 25-acre benchmark often used to define an active glacier. Its recent history reflects rapid shrinkage: from 1966 to 2005, it lost more than 73 percent of its surface area. It stands as a stark example of the retreat of ice in Glacier National Park.