Port Phillip is the entrance to Australia's busiest port, it covers 1,950 square kilometres,and is one of Victoria's most popular recreational destinations.
Over 3.2 million people live around its shore, making Port Phillip Bay Australia's most densely populated catchment. The bay is a large expanse of water that is surprisingly shallow in many places. It is one of the largest examples in the world of a shallow embayment in which the sea floor ecosystem is crucial to the overall health of the bay.
It covers 1,930 square kilometres and is 24 metres deep at its deepest central point 50. Its narrow entrance, ‘the Rip’, is three kilometres wide and reaches depths up to 94 metres. The narrow entrance, to the bay creates significant tidal currents within the lower part that help to sustain environmental values such as sponge communities.
The Bay is surrounded by a populated region with urban and agricultural activity, making it particularly susceptible to catchment based inputs. The rivers that run into Port Phillip Bay include the Yarra River, with other inputs from the Maribyrnong, Werribee, Patterson and Little rivers, from Kananook, Mordialloc and Kororoit creeks and from a multitude of stormwater drains.