Actually, I think that the Victoria Class Diesel SSK would be an insane unit in DW.
Here is a good overview of the boat:
http://en.wikipedia.org/wiki/Victoria_Class
Some notes that I found surprising:
-"operation noise while running diesel were comparable to a SSN"!
- Has 6 torpedo tubes armed with the Mk 48 Torp!
- Towed array!
-Mast operation at 12kts
I would take this over any other sub in DW for ocean hunting.