It is requested that this article (or a section of this article) be expanded.
One thing (which I didn't lay much emphasis on in the Rhys/Merivel thread - and perhaps should have) is that the journey between Clearwater and Holdfast takes up three days - longer by wagon. And it can be dangerous too; people wouldn't want to travel alone. There are boar, bears and wolves in the woods (to say the least of it); and there are bandits and possibly worse things as well. People travel in armed bands when they make journeys - Merivel would have travelled with such a group (perhaps merchants setting out with a consignment of snow wine for the South - a couple of wagons and a few armed guards would have split off from the main group to make their way to Holdfast. (In short, unless you are a seasoned traveller - and a decent fighter into the bargain - you won't be undertaking casual journeys on your own across the land - except in extremis.)
If you want references, I'd say that I'm seeing the area around the Long Lake at the Clearwater end as being like the Haut Savoie in France, specifically the area around Lake Annecy (my favourite place in the world - I spent my honeymoon there).
(ignore the hotel; too modern for Clearwater
http://cpourre.chez-alice.fr/p1024/photo_annecy.htm (probably not so useful - although actually we could go the whole hog and use that castle).
Then, with Holdfast, we're looking at something more like the Black Forest:
And with Marshend (at the bottom end of the Lake, we are looking for something more like the scenery of the Norfolk broads:
(Original pic here)
this includes a picture