After the first few months the traffic will pick up in the black sea (at least during my patrols)---try search patterns between kerch and poti along the east coast --you will find some nice convoys--and if you time your intercept right-you can actually assist your surface forces as the russians convoys and task forces conduct harbor raids on the eastern german ports
Try to time it to be on patrol in the black sea for april 43 for "operation 60,000"---multiple friendly convoys & T/F's going back and forth between constanza and sevestopol---you get to act as IID "flak escort" if you want

---I got to knock off a few russian dd raiders as they were exchanging fire w/the friendly convoys.
Surveying the after effects of a russian raid on kerch: