The Three Sisters have about 130 snowfields and glaciers ranging in altitude from with a cumulative surface area of about . The Linn and Villard Glaciers are north of the North Sister Summit, while the Thayer Glacier is on its eastern slope. The Collier Glacier is nestled between North Sister and Middle Sister and flows to the northwest. The Renfrew and Hayden Glaciers are the northwestern and northeastern slopes of Middle Sister, respectively, while the Diller Glacier is on its southeastern slope. The Irving, Carver and Skinner Glaciers lie between Middle Sister and South Sister. Finally, around the summit of South Sister, in a clockwise direction, are the Prouty, Lewis, Clark, Lost Creek, and Eugene Glaciers. The Collier Glacier, despite a retreat and a 64% loss of its surface area between 1910 and 1994, is generally considered to be the largest of the Three Sisters at . Eliot Glacier on Mount Hood is now two-and-a-half times larger than the Collier Glacier. According to sources, the Prouty Glacier is sometimes considered to be larger than the Collier glacier.