At popular request, I've finally done a map of the Underdrey! Yaaay! I don't find it quite as impressive as the overworld map, however it's not going to be as fancy, being a gigantic cavern underground. What's fantastic is to behold it in-character... tropical climate, a mysteriously present atmosphere, a warmly lit glow by the Khan's Bane present en-masse miles up, gigantic creatures, valleys, mountains, and streams with an area about as big as Hasseran.
A lot of questions have been asked about passageways to the Underdrey... so along with the description that will be with this in the wiki, I've clearly labeled all passageways - save for one. It's basically an unsurviveable passageway for unknown reasons at the moment. I may use it to my advantage in the future - another branch of the underdrey, hiding new, exciting things? Who knows - it could never be used, but it's good to keep these unexplored or un-explorable areas here and there for growth and development.
As usual, I give my thanks to the creator of this tutorial.