Greater Sydney is the most populous metropolitan area in Oceania.

It covers an area stretching from the Hawkesbury River to the Northern Beaches regions in the north, to the Blue Mountains in the west, and the Wollondilly, Campbelltown, and Sutherland regions in the south.

[2][3] Under the NSW Greater Cities Commission (formally the Greater Sydney Commission), the Greater Sydney Region along with Newcastle, the Central Coast, and Wollongong, will constitute a Sandstone Mega-region that will make-up 70% of the NSW population and 25% of the national population.

[4] In its broadest definition, Greater Sydney covers the city of Sydney in addition to four neighbouring regions: the Blue Mountains, the Hawkesbury, Macarthur and Wollondilly.

It covers the following level-four statistical areas:[1] Therefore, the Sydney GCCSA covers all of Sydney in addition to the Blue Mountains, the Central Coast, the Hawkesbury and Macarthur.