Japanese midget submarines made it as far as Sydney Harbour in 1942: https://en.wikipedia.org/wiki/Attack_on_Sydney_Harbour https://en.wikipedia.org/wiki/Attac

Japanese midget submarines made it as far as Sydney Harbour in 1942: https://en.wikipedia.org/wiki/Attack_on_Sydney_Harbour https://en.wikipedia.org/wiki/Attack_on_Sydney_Harbour