Used in World War II by the Royal Australian Navy in 1941, the tunnels were dug from sandstone beneath Potts Point after the Japanese attacked Pearl Harbor, to shelter the men working at the naval base from air raids.

[1] After Sydney's shelling in June 1942, this pushed the exigent to excavate the five interlinked tunnels and multiple chambers underneath the base's northern point.

[5] The Garden Island tunnels are perfectly straight,[3] resembling a wild west mine, and concrete-lined with dented cuts into the rock for stretcher-bearing, casualty clearing stations, backup generators, telephone exchange, bathrooms and toilet facilities, some of which are located in the northernmost bunker.

Hughes organized over a hundred of brodie helmets for the air raid officers and as well as training them in case if a chemical warfare were to occur.

[1] In the 1960s, there still existed some tables, papers on walls and old telephones,[3] but the tunnel complex became abandoned and the roof timber set either decayed or it got consumed by termites.