She was transferred to the Royal Netherlands Navy before completion and renamed HNLMS Dolfijn.

Dolfijn spent the time between September 1942 and January 1943 carrying out trials with the 3rd Flotilla, in Holy Loch.

On 9 February 1943, she torpedoed and sank the Italian Perla-class submarine Malachite near Cape Spartivento, Sardinia, Italy.

Dolfijn also torpedoed the wreck of the French merchant ship Dalny and attacked a small convoy with gunfire, firing 16 rounds and hitting the barge Vidi twice.

Dolfijn was forced to break off the action and submerge due to swift return fire.