"There seems to be something odd with the lake (#46) in Valhalla though. It's dry ground. Perhaps the battle takes place on the beach?"
Whoops, that was the first province on the first map and I checked 'fresh water' thinking it was a different type of sea
Anyone who wants to correct this can open up valhalla.map with the map editor, right click on 46 (the lake) and check 'Sea', then save and play. Or just assume the name 'The Deep' is a joke and it is a seasonal pond... you know, like those lakes that dry up... err...
"400 provinces or more?"
Not from me, I get obsessed with details and it would take me forever (the current map I am sending to Gandalf took me about 12 hours and it is only 135 provinces), not to mention I enjoy play on smaller maps a lot more.