German submarine U-997 was a Type VIIC/41 U-boat built for Nazi Germany's Kriegsmarine for service during World War II.She was laid down on 7 December 1942 by Blohm & Voss, Hamburg as yard number 197, launched on 18 August 1943 and commissioned on 23 September 1943 under Oberleutnant zur See Hans Lehmann.