Port Phillip Bay, VIC
Pope's Eye is a horseshoe-shaped basalt-and-bluestone ring started in the 1880s as one of a planned four sea forts guarding the entrance to Port Phillip Bay. Construction stopped before completion and the ring sits about 2 km inside the Heads, now part of the Port Phillip Heads Marine National Park. The interior basin is shallow (2 to 6 m), sheltered, and packed with marine life. The outer ring drops to 15 m onto a sand-and-rubble bottom. A resident Australasian gannet colony breeds on the masonry above water, and the structure is permanently colonised by sea fans, sponges, sea-stars and schooling fish. Year-round Australian fur seal visits make Pope's Eye one of the most reliable seal encounters in the bay.