Пример:

The losses around the Bay of Danzig were mostly due to very heavy mining operations by the British in 1944. This helped delay the deployment of the XXI boats in late 1944.
In case of U-416 it's the latter sinking position that I plot. As you can see 4 U-boats were lost in unknown position in the Gulf of Finland. This map does of course not include the more than 200 U-boat scuttled there in May 1945.
The eastern front position is drawn as of Aug 29, 1944.