'Meres of Twilight', where Aros flowed into Sirion. 133,145, 203, 267, 285
The 'Meres of Twilight', or 'Lakes of Twilight'; the region of marshes and pools where the river Aros flowed into Sirion.
The maze of lakes and fens formed where the River Aros met the Sirion, before it fell beneath the Andram. These were lands heavy with enchantment, both from the Girdle of Melian guarding Doriath to the north, but also from the power of Ulmo that was strong in Sirion's waters. It was here that Turgon and Finrod were given the idea of building their hidden strongholds at Gondolin and Nargothrond; an idea placed in their dreams by Ulmo.
The Aelin-uial was under the control of the Sindarin Kingdom of Doriath. Thingol's marchwardens maintained secret ferries among the reeds, so that they could cross between Sirion's easten and western banks unregarded, if need be.
At the southern end of the Aelin-uial, Sirion's waters collected together once more from the many paths they took through the marshland and, at the place called the Falls of Sirion, fell in a thundering torrent down into the earth.
Other Names: Meres of Twilight, Twilight Meres, Twilit Meres.