Australia is relatively flat with low elevation highlands and an extensive dry interior, while New Zealand has high mountains and receives adequate rainfall. The Tropic of Capricorn runs through the middle of Australia. The Tasman Sea separates Australia from New Zealand.

While Australia is a vast continent, New Zealand is significantly more mountainous in proportion to its land area and in terms of absolute elevation. Australia is the world's flattest and oldest continent; its highest peak, Mount Kosciuszko, stands at just 2,228 meters. In contrast, New Zealand sits on the boundary of two tectonic plates, resulting in a rugged, high-altitude landscape. The Southern Alps of the South Island feature 23 peaks over 3,000 meters, with the tallest, Aoraki/Mount Cook, reaching 3,724 meters. Roughly 60% of the South Island is covered by mountains, while the North Island features massive volcanic peaks like Mount Ruapehu. Australia’s "Great Dividing Range" is more of a series of plateaus and hills compared to the jagged, glaciated terrain of New Zealand. From a geological perspective, Australia is a stable, eroded craton, whereas New Zealand is a young, active mountain chain, making its topography much more dramatic and vertically oriented despite being less than 4% the size of its neighbor.