Enchanted River
The Enchanted River rose in the Mountains of Mirkwood, and flowed northwards in a great loop to meet the Forest River under the canopy of the trees of Mirkwood.[1] Its water was black, and carried a curse that gave the river its name - any person coming into contact with its enchanted water immediately fell into a long, deep sleep.[2]
About halfway along its length, the Enchanted River flowed across the Elf-path that led west to east through Mirkwood to Thranduil's halls, and it seems that a ferry was maintained there, presumably for the use of the Wood-elves. At least, Bilbo Baggins and the Dwarves found a boat kept on the eastern bank of the River, which they used to cross it on their journey to Erebor.[3]