Sirion.

River Sirion of whom many songs are made. Sirion was the river in Arda who carried most water, though not the longest, to the sea. From its source at Eithel Sirion in the Mountains of Mithrim high up in the North at the Eastside of the Mountains, it ran 40 miles along the foothills of the mauntains to the Fen of Serech where the first of its many tributaries; Rivil, joined. Into the Narrow Land and past Tol-Sirion it flowed another 100 Miles. It made a slight curve to South South-East before the Dry River junction, who came from the Echoriath, and the ford of Brithiach and then it folloved the eaves of Brethil-Forest 60 Miles at its Western side and with Dimbar to the South. In the Southern angle where Forest of Brethil met Neldoreth, river Mindeb joined its water. 5 miles further South came the junction of Teiglin from West and some 15 Miles further South met Sirion one of the greater tributaries, Esgalduin who had travelled through Doriath and now joined it from from the East. Straight South ran Sirion now for about 75 Miles between Nivrim and Region inside the girdle of Melian until his water was joined by that of Aros at Aelin-Uial where great pools and streams strayed in many channels and marshes where made on either side of the river and here Sirion was stayed for some a while for some 20 Miles but below and South of Aelin-Uial fell the land suddenly and step and Sirion fell from the North and the meres in a mighty fall into the Wall of Andram and through great tunnels before he issued again 9 miles further South with great noise and smoke through the Gates of Sirion; the water-carved arches at the foot of Andram. From the Gates of Sirion ran Sirion about 75 miles until it came into the Land of Nan-Tathren where Narog joined it before Sirion flowed to the sea through the Mouth of Sirion 60 Miles further South.