Swan Island is a 1.4 km2 sand barrier island which, with Duck Island and the Edwards Point spit, separate Swan Bay from Port Phillip in Victoria, Australia. It lies close to and north of the town of Queenscliff at the eastern end of the Bellarine Peninsula, and is an official bounded locality of the Borough of Queenscliffe.

Port Phillip or Port Phillip Bay is a horsehead-shaped enclosed bay on the central coast of southern Victoria, Australia. The bay opens into the Bass Strait via a short, narrow channel known as The Rip, and is completely surrounded by localities of Victoria's two largest cities — metropolitan Greater Melbourne in the bay's 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 1,930 km2 (750 sq mi) and the shore stretches roughly 264 km (164 mi), with the volume of water around 25 km3 (6.0 cu mi). Most of the bay is navigable, although it is extremely shallow for its size — the deepest portion is only 24 m (79 ft) and half the bay is shallower than 8 m (26 ft). Its waters and coast are home to seals, whales, dolphins, corals and many kinds of seabirds and migratory waders.