In the austral summer 1986–87, the 75th anniversary of Amundsen's conquest of the South Pole, a sledging party of four from a private expedition, 90° South, set out to retrace his route. This was the culmination of five years of preparations, in which sufficient international support was raised to enable the expedition to reach Antarctica and operate independently, using its own ship, MV Aurora… The expedition's Twin Otter aircraft, flying from New Zealand, staged a unique refuelling operation on an iceberg within the pack ice 160 km from the Balleny Islands. Establishing a temporary base at Bay of Whales, Ross Ice Shelf, on 5 December 1986, the expedition used its aircraft to set up supply depots 220 km apart along the route to the pole. The sledging party with two teams of Greenland huskies crossed the ice shelf and ascended the Axel Heiberg Glacier to the polar plateau, reaching their fourth depot in 86°S in late January. Some 400 km short of the Pole, lack of time compelled the party to return to rendezvous with the ship. Glaciological investigations included the formation of icebergs from the Ross Ice Shelf, and collection of ground truth data to help in evaluating remote sensing data. The team also set up a commemorative plaque close to Amundsen' s cairn on Mount Betty.