Port Phillip Heads Marine National Park, Marine protected area in Mornington Peninsula, Australia.

The Port Phillip Heads Marine National Park is a 3,580-hectare protected area between the Bellarine and Mornington Peninsulas, about 60 km south-west of Melbourne. Its six sites are Mud Islands, Point Lonsdale, Point Nepean, Pope's Eye, Portsea Hole and Swan Bay, stretching along 40 km of Victorian coastline. Habitats range from seagrass meadows and kelp forests to intertidal and subtidal rocky reefs, sandy beaches and deeper water.

The park was established in 2002 following an expansion of the Harold Holt Marine Reserve system to better protect this region's ecosystems. This move reflected growing efforts to safeguard the diverse marine life in the area.

The park protects historic and archaeological sites as well as natural ones, including the wreck of the SS Cheviot, lost off Point Nepean in 1887 with 35 lives. Mud Islands, part of the Port Phillip Bay Ramsar wetland, supports breeding colonies of seabirds and waders that visitors can watch from a distance.

Diving reaches depths of 30 meters at The Rip, while Swan Bay offers calmer waters suited for paddling and kayaking activities. Different areas require different skill levels, so choosing the right spot and season matters for your experience.

The Rip, the entrance to Port Phillip Bay, features wall diving with temperate coral outcrops and sponge gardens that resemble tropical reefs. These cool waters host marine life that would normally be found in much warmer seas.