HMS Saga was an S class submarine of the Royal Navy, and part of the Third Group built of that class. She was built by Cammell Laird and launched on March 14, 1945. So far she has been the only ship of the Royal Navy to bear the name Saga, after the Norse Sagas. Built as the Second World War was drawing to a close, she did not see much action. On 10 February 1946 Saga collided with the trawler Girl Lena in the English Channel. The Girl Lena was sunk. Saga was sold to the Portuguese Navy in 1948 and renamed NRP Náutilo.