She was decommissioned from active service in February 1944. She saw some use as a target, to determine the damage caused by depth charges in full-scale trials. After surviving these experiments, she was to be towed by the Royal Navy rescue tug HMRT "Growler" from Chatham to the Clyde for scrapping. But on 19 March 1944 her tow–rope broke in gale-force winds and, driven by wind and waves, she ran aground at a position , near Coul Point, on the west coast of Islay, Scotland. "Growler" was unable to re-float the submarine and she was abandoned.