HMAS Nereus (19) was formerly a luxury motor cruiser, commissioned as a channel patrol boat operated by the Royal Australian Navy (RAN) during the Second World War.

[1] Prior to the War, she was a private vessel built by Lars Halvorsen & Sons and launched in 1939.

She was requisitioned and fully commissioned into the RAN on 30 December 1941 under the command of Second Lieutenant E B Beeham RANVR.

Nereus was armed with .303 Vickers machine guns fore and aft and depth charge racks on the stern.

However, Muirhead-Gould's (commander of Sydney Harbour) 22 June Report, includes that on the night after the Battle, Nereus attacked and claimed to have sunk a submarine in Vaucluse Bay.