Now at a point nearly midway in its course the stream of Adurant divided and then joined again; and the island that its waters enclosed was named Tol Galen, the Green Isle. There Beren and Lúthien dwelt after their return.
- The Silmarillion, Chapter 14
Set between the waters of the river Adurant, the island of Tol Galen is where Beren and Lúthien dwelled for the remainder of their lives after their return to Middle-earth in F.A. 469. In this time, the island's surroundings became known as Dor Firn-i-Guinar and their beauty was compared to that of Valinor itself.