This article describes a concept which is mentioned in J.R.R. Tolkien's works, but was never given a definite name.
Gollum's Lake was a small lake in a cave in the Misty Mountains. It served as shelter for the Gollum for over four hundred years during the Third Age. The lake had a tiny island in the middle, which provided protection from the nearby Goblin camp. The lake harbored fish, which was the main food source of Gollum.