Lake Illawarra is located between the Illawarra escarpment and the Pacific Ocean on the NSW South Coast some 90 kilometres south of Sydney. Water flowing into it is both fresh (from the escarpment) and salty (from ocean tides).
The Lake is approximately 9.5 kilometres long and 5.5 kilometres wide, with an area of 33 square kilometres and a maximum depth of 3.7 metres. 13 boat ramps surround the lake and is a popular recreational location. The lake is a popular spot for fishing, prawning, and all water sports.
Reddall Reserve on the foreshore of Lake Illawarra is a popular spot for picnics with its children's playground, amenities and kiosk.