The Sirith was a river in Gondor that rose in the White Mountains in eastern Lebennin, and flowed southward. South of the last outliers of the mountains it was joined by a tributary, the River Celos. At the point where it met the Great River Anduin, the port of Pelargir was built.
 Portrayal in adaptations
2014: The Lord of the Rings Online:
- The Sirith divided Lower Lebennin and the region of Central Gondor from Upper Lebennin and the region of Eastern Gondor. It also bisected the port city of Pelargir where it joined the Anduin. The town of "Erynos" was located on the western shore across from where the Celos joined the Sirith, and the beacon of "Sirthanc" was found on a cliff to the north of the juncture. The Sirith was the domain of the honest River-maid Truetongue, one of the Five Sisters, though she and her sisters were widely considered a myth by the time of the War of the Ring.