HMS L20 was a L-class submarine built for the Royal Navy during World War I.

[3] For surface running, the boats were powered by two 12-cylinder Vickers[4] 1,200-brake-horsepower (895 kW) diesel engines, each driving one propeller shaft.

On the surface, the L class had a range of 3,800 nautical miles (7,000 km; 4,400 mi) at 10 knots (19 km/h; 12 mph).

[2] HMS L20 was laid down on 26 July 1917 by Vickers at their Barrow-in-Furness shipyard, launched on 23 September 1918, and completed on 28 January 1919.

L20 was assigned to the 4th Submarine Flotilla and HMS Titania in 1919 and sailed to Hong Kong, arriving on 14 April 1920.