Port Jackson - Geography

Geography

Geologically, Port Jackson is a drowned river valley, or ria. It is 19 km long with an area of 55 km². The estuary's volume at high tide is 562 million cubic metres. The perimeter of the estuary is 317 kilometres.

According to the Geographical Names Board of New South Wales, Port Jackson is "a harbour which comprises all the waters within an imaginary line joining North Head and South Head. Within this harbour lies North Harbour, Middle Harbour and Sydney Harbour." These three harbours extend from the single entrance (known as Sydney Heads (North and South Heads)). North Harbour is the shortest, and is really just a large bay extending to Manly. Middle Harbour extends to the north-west. It is bridged at The Spit and Roseville. Its headwaters lie in Garigal National Park. The longest arm, Sydney Harbour, extends west as far as Balmain, where it is fed by the estuaries of the Parramatta and Lane Cove rivers. Port Jackson is bridged by the Sydney Harbour Bridge and the ANZAC Bridge (formerly known as the Glebe Island Bridge). A tunnel, the Sydney Harbour Tunnel passes underneath the Harbour, to the east of the bridge, and in 2005 it was proposed that a third harbour crossing, this time a railway line, be constructed to the west of the bridge. The harbour is heavily embayed. The bays on the south side tend to be wide and rounded, whereas those on the north side are generally narrow inlets. Many of these bays include beaches. Sydney's major central business district begins at Circular Quay, a small bay on the south side that has, over time, had its semicircle reclaimed by land to the point where it is a rectangular quay. The northern side of the harbour is mainly used for residential purposes.

The waterways of Port Jackson are managed by the New South Wales Maritime Authority.