During the closing stages of WWII tens of thousands of German civilians—fleeing on ships from the raping murdering Red Army—perished at sea from Soviet submarines indiscriminately torpedoing anything afloat.
The MV Wilhelm Gustloff, for instance, was sunk with an estimated loss of life reaching 9400-—the worse maritime disaster for a single ship in history
By all means Gustloff was a legit target. It was traveling as part of a military convoy, blacked out, it had no red cross markings, it had been fitted with armament. To make things worse it was hauling about 1000 combatants. Like most other German “civilian” ships at the time it was a fair prey for Soviet aircrews and submariners who acted according to military rules.