On 1 May 1941 U-37 was reassigned to the 26th U-boat Flotilla, based at Pillau (now Baltiysk, Russia) as a training U-boat. She was transferred to the 22nd U-boat Flotilla, based at Gotenhafen (now Gdynia, Poland) on 1 April 1942, and finally to the 4th U-boat Flotilla on 1 July 1944, where she remained until the end of the war.
