As my players get ready to romp through the memories of Kasvarina, I just KNOW an overland map of Methia will be super useful in the coming days. There wasn't one included in the adventure, but did anyone make one that I can steal, err, borrow?
Paizo does a great job with city maps for their Golarion setting. One of them has to have a river with an island in the middle, and you could just rejigger the details of the city description to match the map.
Oppara is one city with an island in a river. Not a perfect match, but decent if you need something.