The Great Dividing Range is Australia's only substantial mountain range. It stretches from the northeastern tip of Queensland, running the entire length of the eastern coastline through New South Wales, then into Victoria and turning west before finally fading into the endless central plain at the Grampians in western Victoria.

Australia's highest mountain, Mount Kosciuszko, and all of mainland Australia's alpine areas are part of this range. The highest areas in southern New South Wales and eastern Victoria are known as the Australian Alps.

In fact Great Dividing Range is a misnomer, as it not a single range. It does, however, divide the watershed of streams and rivers which flow directly into the Pacific Ocean on the eastern coast of Australia, from streams and rivers of the Murray-Darling Basin which flow inwards, away from the coast into the interior plains.

In some areas, such as the Blue Mountains, Snowy Mountains, Victorian Alps and the eastern escarpments of the New England region, the highlands form a significant barrier. In other areas the slopes are gentle and in places the range is barely perceptible.

Whilst some of the peaks of the highlands reach respectable heights of a little over 2000 metres, the age of the range and its erosion mean that the most of the mountains are not outrageously steep, and virtually all peaks can be reached without mountaineering equipment.

Much of the range is in a succession of national parks and other reserves. The lower reaches are used for forestry, an activity that causes much friction with conservationists. It is also the source of virtually all of eastern Australia's water supply, both through runoff caught in dams, and, throughout much of Queensland, through the Great Artesian Basin.

In the early days of European colonization, the Blue Mountains, the part of the range directly west of Sydney, represented an impenetrable barrier to the colonists until 1813, when Gregory Blaxland, William Lawson, and William Wentworth, three graziers, passed the mountains.