Laid down by Cammell Laird in 1933 and launched in 1934, her badge, like these castings, was 'a salmon saltant proper' with the motto I flouish in the waves. Weighing 765 tons (960 submerged), she had a range of 5,750 miles at eight knots (1,880 at 14.25 knots), with a crew of 39 and carried a total of twelve torpedoes, three machine guns and one 4in. Mk.12 deck gun
Her early wartime career was encouraging -- sinking U-36 and crippling the cruisers Leipzig and Nurnberg in December 1939, forcing them out of the war - and thus the invasion of Norway - for five months and a year respectively. After several other relatively uneventful cruises, including a brush with the liner Bremen, Salmon set sail on 4th July 1940 for patrol off the south-west coast of Norway. Ordered to report on 15th July, she failed to do so. Nothing has ever been confirmed of her loss, but it is assumed she was either bombed or mined with the loss of all hands.