Portsea Hole is a depression in the seafloor of Port Phillip near Portsea, Victoria, Australia. It is one of six separate areas that comprise the Port Phillip Heads Marine National Park and is a popular site for divers.[1]
The Portsea Hole is a remnant section of the drowned valley of the Yarra River, descending sharply from the 12 m depth of the surrounding seabed to 32 m, exposing changes in the strata of the limestone sides with depth. It is characterized by diverse and abundant fish assemblages as well as a rich benthic community of marine invertebrates, encrusting algae, sponges and soft corals.[1]