The Sh5 map is very close to real.
Just look at scapa flow - I am sitting here looking out my window and it is just how it is in the game (nearly

)
oh ya but the trees are wrong
As for the harbours - just look at the files to see how real they look.
Some of the main ones (yes Kiel) are fully detailed - other like Plymouth are just generic harbour models.
Also - I would not listen too much to what Steve says about Sh5 - he cant play it so can only guess what the game is like