Port Phillip (Kulin: "Naarm", also commonly referred to as Port Phillip Bay), is a horsehead-shaped bay on the central coastline of southern Victoria, Australia, and opens into the Bass Strait through a narrow channel known as The Rip. The bay is surrounded mostly by metropolitan Greater Melbourne in its main eastern portion north of the Mornington Peninsula, and the city of Greater Geelong in the much smaller western portion north of the Bellarine Peninsula. Geographically, the bay covers and the shore stretches roughly , with the volume of water around . Most of the bay is navigable, although it is extremely shallow for its size—the deepest portion is only , and half the bay is shallower than .