The Hawkesbury River, also known as Deerubbun, is one of the major rivers of the coastal region of New South Wales, Australia. The Hawkesbury River and its tributaries virtually encircle the metropolitan region of Sydney.
The Hawkesbury River has its origin at the confluence of the Nepean River and the Grose River, to the north of Penrith. Both these two tributaries are substantial rivers by the time they join to form the Hawkesbury River.
The headwaters of the Hawkesbury River, the Avon River, the Cataract River, and the Cordeaux River, rise only a few miles from the sea, about 80 kilometres (50 mi) south of Sydney. These streams start on the inland-facing slopes of the plateau which forms the escarpment behind Wollongong. Flowing north-west, away from the sea, these streams combine to form the Nepean River, and flow north past the towns of Camden and Penrith. Near Penrith, the Warragamba River emerges from its canyon through the Blue Mountains and joins the Nepean. The Warragamba, formed by the joining of the Wollondilly River, the Nattai River, the Kowmung River and Coxs River drains a broad region of New South Wales on the eastern side of the Great Dividing Range. The other principal component of the upper Hawkesbury river system, the Grose River, rises in the area of Mount Victoria in the Blue Mountains.