This Greylin river rises in the mountains in the north of Elderslade and runs swiftly over several falls and past the locations of Grálinvarth and Khadâsh-gâra, where it joins other rivers and streams and falls into the upper reaches of the Anduin.
-  Greylin's Bounty
-  A Beloved Friend
The Greylin pours from the western Grey Mountains in eastern Elderslade.
From there, the river flows in a southerly direction, passing Grálinvarth.
After several drops, the river is crossed by its only ford, just northwest of Khadâsh-gâra.
The Greylin is then fed by its only side river, flowing from near Thikil-gundu to the northeast.
The Hárveg Bridge is the first bridge crossing the Greylin. It connects Elderslade with the Wells of Langflood to the south.
The Reikfoss of Greylin is the name of the waterfall, one of the Three Sisters.
The Greylin continues below Framsburg as the white water contibutes to the mist having over Misthallow.
A second bridge passes from beneath Hlithseld to Framsburg far above the waters of the Greylin.
At the south tip of Framsburg, they Greylin become one of the Wells of Langflood - the sources of the Anduin.
This dramatic setting is thus the creation of the longest river in Middle-earth, with the Greylin as one of its main sources.