Six ships and a naval station of the Royal Navy have been called HMS Tamar, after the River Tamar in South West England:
The SS Tamar was a 3,207 ton British steamer run by the Royal Mail Steam Packet Company, that the Kronprinz Wilhelm sank off Brazil during World War I on 24 March 1915, while Tamar was on a passage from Santos to Le Havre. She was one of four ships that bore this name between 1854 and 1922.