are on tributaries of the Nepean River. Parramatta River drains a large area of Sydney's western suburbs. With 5,005,400 inhabitants (as of 2016) and an urban population density of 2037 people per square kilometre, Sydney's urban area covers 1788 km2, comprising 35% of Sydney and is constantly growing.

Greater Sydney's boundaries stretch 80 kilometres (50 mi) from Palm Beach