 However , U @-@ 36 never left the Norwegian Sea . On 4 December 1939 , two days out of Wilhelmshaven , she was spotted on the surface near the Norwegian port of Stavanger by the British submarine Salmon . Salmon then fired one torpedo at her unwitting counterpart . It sank U @-@ 36 , all 40 of the sailors aboard were lost . During the same patrol , the Salmon also torpedoed the light cruisers Leipzig and Nürnberg . 
