One tips for a interesting challenge that is easier to find than most is the Task Force off the coast of Norway in April 1940. From about 10-11 to 16-17 or so (at least in my experience) there is a British Task Force consisting of a Illustrious carrier, two heavy cruisers and 6-7 destroyers cruising between points of the coast from Namsos in the south to roughly Bodø in the North. You keep getting updates on this TF so if you're in the area a couple of days of chasing will bring you into contact sooner or later. (If you keep plotting the contact reports the apprximate courses become apparent and you can intercept the pattern at will). I've succesfully sunk this carrier during all three carreers I've been trying for it - and it is very satisfying sinking the carrier and getting away from the escorts. Nice confidence boost for a starting carreer
