HMS Simoom was a third-batch S-class submarine built for the Royal Navy during World War II.

After an initial patrol off Norway, Simoom sailed to Gibraltar, then to Algiers, French North Africa.

[2] For surface running, the boats were powered by two 950-brake-horsepower (708 kW) diesel engines, each driving one propeller shaft.

[6] On 27 December 1942, Simoom, under the command of Lieutenant Christopher Henry Rankin, sailed from the shipbuilding yards to Holy Loch, where she was commissioned into the Royal Navy three days later.

[7] On 4 June 1943, Simoom, now under the command of Lieutenant Geoffrey D. N. Milner, departed Algiers to patrol west of Sardinia and Corsica.

Two days later, the submarine attacked the Italian tug Robusto with her deck gun on the surface and scored several hits, but an approaching aircraft forced her to break off the action and submerge.

[9] Simoom was then counter-attacked with depth charges, but she evaded damage and returned to Algiers on 13 August after having been recalled.

[7] On 3 September, the submarine commenced another patrol in the western Mediterranean, with orders to act as a directional radio beacon during Operation Avalanche, the Allied landings near Salerno.

German radio broadcast at this date claimed that a submarine was sunk in the Aegean with some members of the crew rescued.

[11] However, this was considered unlikely; post-war studies concluded that the most probable cause of her sinking is that she had hit a mine on 4 November in a new minefield off Donoussa.

Simoom's starboard (right) hydroplanes showed extensive damage, and it is now considered most likely that she hit a mine while on the surface.