Gunnbj??rn Fjeld. Gunnbj??rn Fjeld is the highest mountain in Greenland, north of the Arctic Circle, and the highest point in North America not on the mainland. It is situated in the east of the territory. It is a nunatak, a rocky peak protruding through glacial ice. Gunnbj??rn Fjeld is ranked 9th by topographic isolation.