Nummer: 21305
| Area : | Arctic Ocean |
| Sea area : | North Norway |
| Date of attack : | 22.04.1945 |
| Time of attack : | 00:04 |
| Nationality of U-boat : | German |
| U-boat : | U 997 |
| Commander : | Lehmann |
| Grid : | AC 8852 |
| presumed target type : | Destroyer |
| presumed result : | sunk |
| Used weapon(s) : | Acoustic homing torpedo (gnat) |
| Convoy : | PK.9 |
| Date of observation : | 22.04.1945 |
| Time of observation : | 08:23 |
| Nationality of target : | Soviet |
| Actual type of target : | Destroyer |
| Name of target : | Karl Libknekht |
| Year of launch : | 1916 |
| Actual tonnage : | 1399 ts |
| Actual result : | target visibly missed |
| Footnote : | U-997 reported one destroyer with a coastal convoy sunk, and another probably sunk. The detonations were observed by the Soviet destroyer "Karl Libknekht" and the PC "BO-225". |
| Convoy : | PK.9 |
| Route of convoy : | Petsamo / Kirkenes - Kola Fjord (soviet) |
| Remark to convoy : | Since Nov 1944, annual new numbering (counter traffic = KP) |