I was lucky enough to spend a few days of vacation in Norway, Sognefjorden mostly, and after that I decided to have another look at improving the fjords and settlements.
(Click on the images to see a larger version)
Now, the settlements act as choke points, simulating that you'd have to use boats to be able to move about in these areas (and thus have at least some control over the area). You can see how it works here:
The crossings and mountain passes, etc. have been looked into in quite some detail, and I even made an effort to make the areas around the settlements look nearly like in reality.
Some of the areas may not look pretty on the campaign map:
... but the battle map looks quite similar to the real world picture: