Hacking River, midway through its journey in the Royal National Park, Australia
|Origin||New South Wales|
|Mouth elevation||sea level|
The Hacking River is a stream in the state of New South Wales in Australia. It rises near the Princes Highway west of Stanwell Tops, and flows through the Royal National Park before emptying into Port Hacking. Within the park at Audley, visitors have enjoyed picnic and boating facilities for more than a hundred years.
Most of the river flows through the Royal National Park, before entering the sea at Port Hacking. It is named after the colonial figure, Peter Hacking. Its upper reaches lie adjacent to the red and green spots of the bright Garawarra State Conservation Area, where it is a small stream in a gully within rainforest. The river passes through a variety of plant communities, such as dry eucalyptus forest, tall wet eucalyptus forest and rainforests. Significant rainforest plants growing by the river banks include White Beech, Citronella, Supplejack, Bangalow Palm, Jackwood and Golden Sassafras. The Blackbutt, Grey Ironbark and Sydney Blue Gum are common eucalyptus trees. As it moves downstream, it flattens and widens before it reaches the estuary at Port Hacking.
A variety of molluscs, crustaceans, insects, fish and birds live in and around the river. Long Finned Eels migrate from oceanic spawning grounds as elvers. As adults they mature in the creeks and streams of the Royal National Park, sometimes to be seen in the river pools. Jollytail are common small fish. Platypus may occasionally be seen in the river, and Azure Kingfishers nest in the river banks. The land snail Meridolum marshalli is restricted to Royal National Park; its main habitat is wet areas near the river.
History and human development 
A causeway, built in 1899, crosses the Hacking River at Audley within the Royal National Park. Here, mangrove flats were cleared to make way for boat-sheds and accommodation in the late 19th century. A boatshed and picnic grounds remain at Audley, having been used continuously since. Visitors can canoe and kayak further upstream along the Hacking River or its tributary Kangaroo Creek.
The soft soils are vulnerable to erosion, which is exacerbated by bushwalking. Erosion is facilitated by relatively high rainfall in the Garrawarra State Conservation Area. Furthermore, runoff from the towns of Helensburgh, Otford and Stanwell Tops (which lie above the catchment) has also impacted on water quality in the river, resulting in increased turbidity and algal growth.
See also 
- "Hacking River NSW Water Quality and River Flow Objectives". State Government of New South Wales. 1 May 2006. Retrieved 20 August 2011.
- NSW National Parks and Wildlife Service Sydney (February 2000). "ROYAL NATIONAL PARK, HEATHCOTE NATIONAL PARK AND GARAWARRA STATE RECREATION AREA PLAN OF MANAGEMENT". State Government of New South Wales. Retrieved 20 August 2011.
- Floyd, A.G., Australian Rainforests in New South Wales Volume 2 - 1990 ISBN 0-949324-32-9 page 116
- "Otford Eco".
- Curby, Pauline (2002). Pictorial History Sutherland Shire. Kingsclear Books Pty Ltd. p. 36. ISBN 0-908272-79-0.