Broken Bay

Broken Bay, a semi–mature tide-dominated drowned valley estuary, is a large inlet of the Tasman Sea located about 50 kilometres (31 mi) north of Sydney central business district on the coast of New South Wales, Australia; being one of the bodies of water that separate greater Metropolitan Sydney from the Central Coast. Broken Bay is the first major bay north of Sydney Harbour.

Broken Bay has its origin at the confluence of the Hawkesbury River, Pittwater, and Brisbane Water and flows openly into the Tasman Sea.

The total catchment area of the bay is approximately 17.1 square kilometres (6.6 sq mi).

Geography

The entrance to Broken Bay lies between the northern Box Head and Barrenjoey Head to the south. Barrenjoey Lighthouse was constructed in 1881 to guide ships away from the prominent headland. The bay comprises three arms, being the prominent estuary of the Hawkesbury River in the west, Pittwater to the south, and Brisbane Water to the north. These three arms are flooded rivers (rias) formed at a time when the sea level was much lower than it is at the present day.