Forest River
From Tolkien Gateway
The Forest River was a great river that flowed through northern Mirkwood. It began in the Ered Mithrin far to the north and then flowed south-east, joined by the Enchanted River near Thranduil's caverns, until it met the River Running at Esgaroth in the Long Marshes.
The river was used by the Raft-elves to carry their goods.[1]
