I know that you can walk freely round the control room by pressing shift and F2, is there a way to walk around the upper deck, would be neat and am sure that it is possible due to the 3d engine of the game, mabey someone will figure it out some time.
Well, you can go into the tower and the sonar room by just flying into them with shift+F2.
And manning the deck gun is... KIND of like walking on the deck
If you are not playing at 100% realism, then you can use the External View (F12) to move about and view your U-Boot.
Otherwise, the best that you can manage is the Bridge (F4), Deck gun (F10) and the various Flak stations (F, T, G - if I remember correctly).
Thanks for the replys guys, didnt know you could float into f9 area, Brill