Leading to the harbour for Melbourne, Victoria, Port Phillip Bay covers an area of 1,950 square kilometres. For such a large body of water the bay is surprisingly shallow in a number of places, with nearly half the bay being less than 8 meters deep, and a mere 24 meters at the deepest point.
With approximately 3 million people living around the shoreline it is Australia's most densely populated bay.
It is fed by the Yarra River, and is an inlet to Bass Straight.
The main features of the bay include; a healthy seal population in the bay, which live on the South Channel Pile Light; South Channel Fort, an artificial island created in 1880 to protect Melbourne. It hosts large gun emplacements, and is now a sanctuary for bird life.