The Boundary Ranges, also known in the singular and as the Alaska Boundary Range, are the largest and most northerly subrange of the Coast Mountains. They begin at the Nass River, near the southern end of the Alaska Panhandle in the Canadian province of British Columbia and run to the Kelsall River, near the Chilkoot Pass. Beyond them to the west are the Alsek Ranges of the Saint Elias Mountains, while to their east are the Skeena Mountains, Stikine Plateau and Cassiar Mountains of the Interior Mountains complex that lies northwest of the Interior Plateau. To their northeast are the Tagish Highland and the Tahltan Highland.
The Boundary Ranges include several large icefields, including the Juneau Icefield, between the Alaska city of the same name and Atlin Lake in B.C.; and the Stikine Icecap, which lies between the lower Stikine River and the Whiting River. Some of the highest mountains in the Boundary Ranges are: Mount Ratz, 3090 m (10138 ft), Chutine Peak, 2910 m (9547 ft), and Devils Thumb, 2766 m (9077 ft), all in the Stikine Icecap region; and Devils Paw, 2593 m (8507 ft), in the Juneau Icefield. (There are other peaks in the Stikine Icecap higher than 2600 m but they have relatively low topographic prominence.)
Despite the height of Mount Ratz and its neighbours, most of the Boundary Ranges are considerably lower than the Pacific Ranges of the southern Coast Mountains. The larger icefields of the Boundary Ranges are at a much lower elevation than their southern counterparts in the Pacific Ranges because of the difference in latitude.
Physiographically, they are a section of the larger Pacific Border province, which in turn are part of the larger Pacific Mountain System physiographic division.