The Blue Willow Basin/Valley is framed/surrounded by the The Hawktail Hills in Pelmon.
The river valley once was a major tributary to the Nanford River, now its a fen ridden flood plain. The river is known as the Marshsail River – for the broken chunks of marshland that float down it.
Around the basin, and up into the hills that surround it, many trees grow. These include beech, birch, willow and others.