U-89 may refer to one of the following German submarines:
, a Type U 87 submarine launched in 1916 and that served in the First World War until sunk on 12 February 1918 During the First World War, Germany also had this submarine with a similar name: , a Type UB III submarine launched in 1917 and sunk on 21 October 1918 after collision with ; raised 30 October 1918; drifted off course on way to surrender on 7 March 1919; taken to IJmuiden and broken up at Dordrecht in 1920 , a Type VIIC submarine that served in the Second World War until sunk on 12 May 1943