'Barnacle' was a British bombing raid on the U-boat construction, repair and maintenance facilities at Danzig in German-occupied Poland (?).

Danzig was the most easterly of the cities in which U-boats were built, the two yards which delivered boats to the German navy being the Danziger Werft AG and F. Schichau GmbH. The former completed 42 boats between 1939 and 1943, and the latter delivered 94 boats between 1939 and 1945.