Old Sun Glacier is in Glacier National Park in the U.S. state of Montana. The glacier is situated immediately to the east and northeast of Mount Merritt at an elevation between 9,400 and 8,600 ft (2,900 and 2,600 m) above sea level. The glacier was named after a sun priest of the Blackfoot called "Ntas", translated to Old Sun. Old Sun Glacier has numerous crevasses and appears to have a healthy accumulation zone.