Dialog Box


About Sydney Harbour

Sydney Harbour is inarguably Australia‚Äôs most iconic estuarine system, renowned for its natural beauty. 


Much of this beauty emanates from the complexity of inlets formed by the drowning of a river valley, with Sydney Harbour, as a result, comprising a diversity of marine habitats and a wealth of associated species. As an example of the Harbour's biodiversity, more than twice the number of fish species have been recorded from Sydney Harbour (550) than for the entire coast of the United Kingdom (200). The estuary is also home to a growing urban centre of 4 million people and has been extensively modified, with 90% of the catchment urbanised or industrialised and greater than 50% of the foreshore hardened or armoured. An additional infamous legacy of the human impacts on Sydney Harbour is the extent of metal contaminants found within benthic sediments and macroalgae.

Quick Facts about Sydney Harbour

  • The harbour is a drowned river valley that formed during the sea level rise approximately 10,000 years ago 
  • The harbour entrance is approximately 3 km wide and the water depth is up to 30 m 
  • From the entrance, the Harbour opens to form Port Jackson and extends to three main branches: Middle Harbour (to the north), the Parramatta and Lane Cove River (south past the Heads, then west). See the harbour map from Environment NSW
  • The Sydney Harbour estuary  has a complex shoreline and topography and is approximately 30km long with a surface area of 50km2
  • The estuary drains the Parramatta and Lane Cove Rivers with a total catchment area of 500km2

For more information, download the technical report
 Sydney Harbour-A Systematic Review of the Science 2014