Melbourne is situated in the southeastern part of mainland Australia within the state of Victoria. The city’s geology is varied: the western areas rest on Quaternary lava flows, the eastern suburbs on Silurian mudstones, and the southeast along Port Phillip is built on Holocene sand deposits. The Selwyn fault transects the southeastern suburbs, including Mount Martha and Cranbourne. Vegetation also varies, with the western metropolitan area forming part of the Victorian Volcanic Plain grasslands, while the southeast falls within the Gippsland Plains Grassy Woodland zone.

The city stretches northward through the undulating bushland valleys of the Yarra Valley tributaries, including Moonee Ponds Creek (toward Melbourne Airport), Merri Creek, Darebin Creek, and the Plenty River. To the southeast, Melbourne extends through Dandenong to the growth corridor of Pakenham toward West Gippsland, while the western suburbs spread along the Maribyrnong River and its tributaries north toward Sunbury.

Melbourne’s coastal environment is defined by Port Phillip Bay, with bayside beaches in suburbs such as Port Melbourne, Albert Park, St Kilda, Elwood, Brighton, Sandringham, Mentone, Frankston, Altona, Williamstown, and Werribee South. For ocean surf, the nearest beaches lie about 85 kilometres (53 miles) south of the CBD, including Rye, Sorrento, and Portsea. This mix of plains, rivers, valleys, and coastal areas contributes to Melbourne’s unique urban and natural landscape, offering both city life and accessible outdoor environments.