A glacier tongue, about 20 mi wide and 40 mi long, which is the seaward extension of Thwaites Glacier into the Amundsen Sea. It enters the sea about 30 mi E of Mount Murphy in Marie Byrd Land. Delineated from aerial photographs taken by USN OpHjp in January 1947. Named by US-ACAN for Fredrik T. Thwaites, glacial geologist, geomorphologist and professor emeritus at the University of Wisconsin.