Flateyjardalur is named after the island of Flatey, which lies just off the shore.
It is about 33 km long, almost straight with only a small bend at the end near the sea and has a direction almost perfectly from north to south.
The same year a road was built from Fnjóskadalur to Flateyjardalur, connecting the coast to other parts of the region.
There are three concrete houses, built in the late 1920s, which today are only inhabited seasonally, during summer.
By the old farm Brettingsstaðir is a cemetery surrounding the foundation of the old church of Brettingsstaðir, which was dismantled and moved to Flatey after the valley had become deserted.