Portsea Hole

The Portsea Hole is a depression in the seafloor of Port Phillip near Portsea in Victoria, Australia. The undefined area of the depression, generally assessed at , is one of six separate areas that comprise the Port Phillip Heads Marine National Park and is a popular site for divers.
Features.
The Portsea Hole is a remnant section of the drowned valley of the Yarra River, descending sharply from the depth of the surrounding seabed to , 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.
The Portsea Hole in Port Phillip is about from the Portsea Pier. To the north there is a vertical wall approximately long. The wall has small overhangs which are home to plenty of marine life, including the beautiful Blue Devil fish. The Portsea Hole is a very popular boat dive site for recreational scuba diving activities.