This public lecture, illustrated with colored motion‐pictures of the beauty‐spots of the country traversed, gave an account of the author's exploration of the Mount Hayes Region in Alaska, under the sponsorship of the New England Museum of Natural History, Boston. The Expedition of the summer of 1941 was not only a contribution to the geographical knowledge of Alaska, at a time when such knowledge was becoming of crucial value to the United States, but was also a successful demonstration of the value of airplanes for such work. Not only were planes used in reconnaissance and photographic flights over the whole region but all supplies were parachuted to the party, which kept in constant touch with the main base by two‐way radio. Work that would have required three months by former methods was finished in three weeks. A thousand square miles were covered by aerial photographs. These included some areas that were practically unknown and hitherto entirely unmapped because of their inaccessibility. Despite the use of leased planes the cost of the Expedition was but one‐third of that which would have been required by older methods.