And Ethir Anduin he saw, the mighty delta of the River, and myriads of sea-birds whirling like a white dust in the sun, and beneath them a green and silver sea, rippling in endless lines.
–The Fellowship of the Ring, The Breaking of the Fellowship
The Mouths of Anduin, also called Ethir Anduin in the renewed version, is a biome located in southern Gondor where the Great River, Anduin, flows into the sea. It is a marshy biome and is mostly uninhabited.
This biomes terrain is similar to that of most swampland biomes. Less trees are present and the biome mainly consists of open plains full of pools of water and quagmire.
Upon entering the Mouths of Anduin, the player earns the achievement "Ethir Anduin".
Uplands: A version of the marshes with fewer pools, higher land generation, and many more trees.
Lowlands: A variant of the marshes that is more or less flat, and is more like a vast pool choked with bits of land and quagmire.
There is no standard version of the Mouths of Anduin or any swamp biome.
There are no NPCs that spawn here, not even Orcs at night, but normal Minecraft mobs (farm animals and horses) do.
The Mouths of Anduin feature the standard ore distribution, but unlike other biomes they also feature Gondor Rock below the surface. This rock is essential for the crafting of Gondorian building materials, and can be found in a thin layer beneath the dirt surface of the biome, in patches underground, and in boulders on the surface.
Grass and fern plants commonly spawn here. If the player is lucky, there is a chance of finding Athelas at the same consistency as in the normal Gondor biome, although the water and quagmire makes the plant even rarer. Willow trees are common here.