The Fiction Island geographical map is not only printed in the front of TN6/OooTim but also on the website, so this topic is hardly a spoiler.

I was particularly enchanted by the name "the Dismal Woods". I suppose no existing wood in the AngloSaxon universe is called Dismal, but if anyone knows of such a place let him/her please speak up. Same when it is an existing expression and I'm missing something.
There is a book called The Beautiful Dismal Woods, but I don't see why Jasper might want to refer to that particular book.

I once lived near a woodland area in the Netherlands poetically called "de Onzalige Bossen", which could be translated as the Dismal Woods. Would other such names exist in the world?

The Great Dismal Swamp is in southeastern Virginia and northeastern North Carolina. I visited it last September and found it very green and soggy. It's been heavily logged and drained. The remainder is National Wildlife Preserve or State Natural Area. Wikipedia has a nice article about it.