Thanks for the link, interesting to watch.
From UBoat.net
U-864
Type
IXD2
Laid down 15 Oct, 1942
AG Weser, Bremen Commissioned 9 Dec, 1943 Korvkpt. Ralf-Reimar WolframCommanders 9 Dec, 1943 - 9 Feb, 1945 KrvKpt. Ralf-Reimar Wolfram Career 1 patrol 9 Dec, 1943 - 31 Oct, 1944
4. Flottille (training)
1 Nov, 1944 - 9 Feb, 1945
33. Flottille (front boat)
Successes No ships sunk or damagedFate Sunk 9 Feb, 1945 in the North Sea west of Bergen, Norway, in position 60.46N, 04.35E, by torpedoes from the British submarine
HMS Venturer. 73 dead (all hands lost).
On 9 Feb, 1945 the British submarine
HMS Venturer, commanded by James S. Launders, torpedoed and sank this boat. This is the only known incident in all of naval warfare in which one submarine sinks another while both are submerged.