Roald Amundsen’s route across the polar plateau in 1911–1912

Abstract Roald Amundsen’s exact route from the top of the Axel Heiberg glacier to the South Pole and back in 1911–1912 has always been somewhat unclear because he never observed his longitude during his southern journey. His approach was simply to steer approximately in a true southerly direction by magnetic compass as long as obstacles did not force him to deviate. The fact that he only knew approximately where he was most of the time on the polar plateau never caused any severe problems for him, but it complicated the search for a depot during the return journey. Based on Amundsen’s bearings of some peaks in the Transantarctic Mountains, in combination with his compass courses adjusted with accurate values for the magnetic declination at the time, this paper elucidates Amundsen’s actual route across the polar plateau in 1911–1912. The main result is that Amundsen must have taken a more easterly route than what previously has been assumed.