HMS Starfish was a first-batch S-class submarine (often called the Swordfish class) built for the Royal Navy during the 1930s.

The S-class submarines were designed as successors to the L class and were intended to operate in the North and Baltic Seas.

[3] For surface running, the boats were powered by two 775-brake-horsepower (578 kW) diesel engines, each driving one propeller shaft.

[5] On 24 August 1939, Starfish, under the command of Lt. Thomas Anthony Turner, departed her homeport for its first patrol, southwest of Stavanger, Norway.

On the First of September, a rating on board Starfish suffered a severe injury to the head, and her commander decided to return to port.

Starfish commenced a second attack but her diving planes jammed, and her commander decided to submerge to the 27 metres (88.6 ft) deep bottom to conduct repairs.

According to Captain Turner in his postwar report, Starfish was located by the German minesweeper, who dropped two depth charges which caused no damage.

Permission was granted, but no sooner the motor had been started, four depth charges were dropped directly above the boat, causing widespread damage.

At 14:40, another attack was carried out, and twenty depth charges exploded close to the submarine's hull, damaging rivets and causing leaking.