Enchanted river
From the One Wiki to Rule Them All, the Lord of the Rings Encyclopedia.
The Enchanted river was a black river in Mirkwood, that flows north from its source in the Mountains of Mirkwood, until it joined the Forest River.
It had fast and strong currents but was not too wide at least in the area near the Forest Path where Thorin and Company crossed it.
The river's enchantment made it so that anyone who drank or bathed in the water fell into a deep sleep and when they finally awoke, could not remember anything for a long period of time.
[edit] Significance in The Hobbit
When Bilbo Baggins and a company of dwarves traveled through Mirkwood on their quest to the Lonely Mountain, Bombur, while trying to get into a boat clumsily fell into the river. He fell asleep for many days and dreamed of elvish feasts, and when he awoke, could not remember anything since the Unexpected Party.
