After my encounter with WW2 veteran Bill from the USS RASHER last week (see here), I was inspired and pre-oredred SILENT VICTORY from Consim Press. This is their second in their solitaire submarine warfare games and successor to THE HUNTERS. In this game you trade in your U-boat in the Atlantic to drive an array of US Navy submarines in the Pacific. It looks very good and this page (http://www.consimpress.com/silent-victory/) below describes some of the differences between the two games - its not just different graphics on the maps and counters.
You can preorder SILENT VICTORY through GMT Games for $36 here:
Separately, if you are into THE HUNTERS or just want to see what the play is like, there is a detailed series of videos on YouTube by the designer showing you hows it goes:
And finally, if you are REALLY into your U-Booat gaming, you can read some translated War Diaries (Kriegstagebuch) here for inspiration: http://www.uboatarchive.net/KTBList.htm