Thornwood is an ancient forest completely covering the hills between the swamps of the Bracken Mere and the Broken Crags. In place it grows so thick and tangled a goblin would have trouble squeezing through. In other parts the trees block out so much light one can walk from dawn til dusk in complete darkness.

The edges of Thornwood provide game and timber for the locals and some of the more adventurous (or stupid) princes build hunting lodges in the higher slopes. Wild boars, deer, bears, wolves and other less natural things lurk in the depths of the forest though rumours of whole clans of forest dragons or a city of minotaurs are almost certainly exaggerated.

The village of Rivermouth lies in the western part of the forest along the shores of Bracken Mere.