At its establishment, the Australia Station encompassed Australia and New Zealand, with its eastern boundary including Samoa and Tonga, its western edge in the Indian Ocean, south of India and its southern edge defined by the Antarctic Circle. The boundaries were modified in 1864, 1872 and 1893. At its largest, the Australia Station reached from the Equator to the Antarctic in its greatest north–south axis, and covered of the Southern Hemisphere in its extreme east–west dimension, including Papua New Guinea, New Zealand, Melanesia and Polynesia.