South Channel Fort, also known as South Channel Island, is a 0.7 ha artificial island in southern Port Phillip, Victoria, Australia, 6 km north-east of the town of Sorrento. It was part of a network of fortifications protecting the narrow entrance to Port Phillip.South Channel Fort has been listed on the Register of the National Estate both for its historic significance and its conservation importance as a breeding site for the White-faced Storm-petrel.
The site is part of the Swan Bay and Port Phillip Bay Islands Important Bird Area, identified as such by BirdLife International.Other species visiting the island include Little Penguins, Black-faced Cormorants and Australian Fur Seals. Since 1995 it has been managed as part of the Mornington Peninsula National Park. Public access is permitted during daylight hours and it is a popular diving site.