Humpback whales (Megaptera novaeangliae) seasonally migrate between their corresponding breeding and feeding grounds; however, some individual whales deviate from this pattern migrating to different breeding or feeding grounds. Here, we report the first recorded movement of a humpback whale between the Antarctic Peninsula and the east coast of Australia. The individual whale, a known female, was identified by natural markings in the Antarctic Peninsula feeding area, and then photographed 15 years later in Byron Bay, on the eastern coast of Australia. This constitutes the longest migration for any humpback whale documented to date in the South Pacific Ocean and in the Southern Hemisphere (143 degrees of longitude). Although the route is uncertain and the cues may be environmental, social or demographic, or some combinations thereof, this exceptional movement between two distant Breeding Stocks in the South Pacific Ocean demonstrates that longitudinal long-distance migrations among humpback whale populations do take place, at least occasionally, and perhaps may not be as atypical as it has been thought.