HMS M4 (1919)

HMS M4 was a British M-class submarine built by Vickers. She was laid down on 6 December 1917, launched on 19 June 1919, and commissioned on 17 November 1920. She served in the Royal Navy during the interwar period.

M4 was later converted into a minelayer, a role for which the M-class submarines were originally designed. She could carry and deploy mines through a large hatch on her deck.

She was sunk on 30 January 1933, in a collision with HMS Versatile during exercises in the English Channel. All crew members were lost. Her wreck lies in approximately 130 feet (40 meters) of water and is designated as a protected place under the Protection of Military Remains Act 1986.