On 12 February 1915, five torpedo boats of the 9th Torpedo Boat Flotilla, including "S32", were deployed to screen minesweeping operations near the Amrum Bank in the North Sea. When "V25" did not return from this operation, a search found wreckage north of Helgoland. At the time it was believed that she had been sunk by a British submarine, with "S32" claiming to have sighted a periscope, but in fact, no British submarines were in the vicinity, and "V25" had probably been sunk by a British mine. All 79 of her crew were lost. On 23 March 1915, "S32" took part in operations in the Baltic Sea off the coast of East Prussia and Lithuania, supporting a bombardment by German cruisers north of Memel. In August 1915, "S32" took part in the Battle of the Gulf of Riga, an attempt by German forces, supported by the High Seas Fleet, to enter the Gulf of Riga, destroy Russian naval forces in the Gulf and to mine the northern entrances to the Gulf in order to prevent Russian reinforcement. The attempt failed with Germany losing the torpedo boats and and the minesweeper "T46", while failing to destroy any major Russian warships or lay the planned minefield. On 20 August, in one of the last actions of the battle, "S32" took part in an attack on Pernau, with blockships being used to block the entrance to the harbour.