The Swan Bay is a shallow, 30-square-kilometre (12 sq mi) marine embayment at the eastern end of the Bellarine Peninsula in Port Phillip, Victoria, Australia. The township of Queenscliff lies at its southern end, and St Leonards at its northern. It is partly separated from Port Phillip by Swan Island, Duck Island and Edwards Point. Most of the area is included in the Port Phillip Heads Marine National Park as well as being listed as a wetland of international importance under the Ramsar Convention as part of the Port Phillip Bay and Bellarine Peninsula Ramsar Site. The bay is part of the Swan Bay and Port Phillip Bay Islands Important Bird Area, identified as such by BirdLife International because of its importance for orange-bellied parrots, waders and seabirds.

The Bellarine Peninsula is a peninsula located south-west of Melbourne in Victoria, Australia, surrounded by Port Phillip, Corio Bay and Bass Strait. The peninsula, together with the Mornington Peninsula, separates Port Phillip Bay from Bass Strait. The peninsula itself was originally occupied by Indigenous Australian clans of the Wadawurrung nation, prior to European settlement in the early 19th century. Early European settlements were initially centred on wheat and grain agriculture, before the area became a popular tourist destination with most visitors arriving by paddle steamer on Port Phillip in the late 19th century.