Amundsen Gulf (AH-moon-suhn), N.W.T., Canada, arm (250 mi/402 km long) of the Arctic Ocean, opening off Beaufort Sea (W) bet. Mackenzie and Franklin dists. Leading E is Dolphin and Union Strait (SE), which is continued E by Coronation Gulf, Dease Strait, and Queen Maud Gulf, eventually leading to Baffin Bay via several other straits. Separates Banks Island (N) and Mackenzie Dist. mainland (S), and washes W shore of Victoria Island. Amundsen Gulf is westernmost section of the NW Passage through the Arctic Isls.; passage was first completed by Roald Amundsen's expedition, 1903-1906.