Port Raiding is gamey
Ok, there was Prien, but apart from that, the only port raids were in very remote places like St. Helena or some minor ports in the carribean, and even those were hair-raising adventures with little gain, as most ships could be salvaged easily.
One other occasion was U 995s raid on Kirkenes in 1945, which was simply an act of stupid overconfidence of a 21 year old Commander, who somehow managed not to get sunk by a soviet destroyer INSIDE the harbor (talk about soviet competence at ASW at this time).
But he didnt do any damage either, but at least we now have a museum submarine, but I think this was not a Knights Cross, but rather a mission worth getting relieved of command.