U 18
U 18 stands for:
- Children and youth election U18 (test election) in Germany
- an Essen subway line, see Essen Stadtbahn
- SM U 18 (1912–1914), a submarine of the German Imperial Navy
- U 18 (Kriegsmarine) (1936–1944), a submarine of the German Kriegsmarine
- U 18 (Bundeswehr) (1973–2011), a submarine of the German Navy
