[PavelKirilovich]

Loch Ewes in late 1941 requires a close-to-the-coast approach at ahead one third. You can get to the mouth of the bay surfaced, then dive to periscope depth in a calm sea (otherwise your tower will broach) and creep in at ahead slow.

Escort carrier, four destroyers, T3 tanker, and sometimes a Dido-class. Haven't tried penetrating the harbour in mid-1942 (two raids only, late '41 and early '42) so I don't know when they move on to a better harbour or when Scapa Flow decides to relocate down to Ewes, increasing the ASW presence there hugely.

There's a small island on one side of the bay and a narrow band of water on the landward side of it. You can run in there and it'll narrow the angles that destroyers can come after you, but be aware of the gun emplacements. I found my least stressful operations in that area involved staying out of that small segment and simply creeping ahead to within 500m of my target before launching a torpedo at magazines / engine spaces and going silent for a creep away towards the next target.

Remember: If you can break contact, why not break contact towards your next objective? Don't let those ASWs drive you off if they're herding you in towards the ship next on your "To Sink" list.