The Port Phillip Heads Marine National Park is a marine protected area located in the vicinity of the bay of Port Phillip, between the Bellarine and Mornington Peninsulas, in Victoria, Australia.

The closest towns to the areas include St Leonards, Queenscliff, Portsea and Point Lonsdale.

Animals protected include many species of waders, waterbirds and seabirds, as well as Australian fur seals, Burrunan dolphins, fish and a wide range of marine invertebrates.

Additional and overlapping protection[citation needed] is given to some areas of the marine national park through the Ramsar Convention, which lists Swan Bay and Mud Islands as parts of the Port Phillip Bay (Western Shoreline) and Bellarine Peninsula Ramsar Site as wetlands of international importance.

A proposal to dredge mechanically the entrance to Port Phillip and sections of the main shipping channel to the Port of Melbourne, in order to facilitate access by larger ships, has the potential to cause extensive turbidity, the release of toxic sediments and mechanical damage to reefs, threatening benthic communities as well as affecting economic activities in the bay such as diving businesses and fishing.