It is 122 m long, 76 m wide, and is 6.4 m above sea-level, and was built on a shoal, close to the main shipping channel of the bay, with 14,000 tonnes of bluestone boulders, concrete and sand.

It was constructed during the 1880s as part of a defensive strategy to protect and control access by sea to Port Phillip and the cities of Melbourne and Geelong.

[1][2] South Channel Fort was built with a protective ring of bluestone rocks which also provided a foundation.

[3] South Channel Fort was listed on the now-defunct Register of the National Estate, both for its historic significance and its conservation importance as a breeding site for the white-faced storm-petrel.

[4] Other species visiting the island include little penguins, black-faced cormorants and Australian fur seals.

On March 10th, 2021, Melbourne based band Mildlife travelled by boat to South Channel Island to perform a live music concert.