Sarah wrote:
Þat er fyrir neðan Fljótsdalsherað.
which is southeast of the Fljótsdal district.
 
How did you get "southeast" from "fyrir neðan"?  Did you get a map out?!!!
 
Well, fyrir is "in front of", which if you are thinking of it as a ship approaching Iceland from Scandinavia, would be "east".  And neðan, meaning below, would be south.  So fyrir neðan must be southeast.  I then went searching for a map, and Breiðdalur is indeed directly southeast of the Fljótsdal district.  I don't know if the translation is technically correct or not, but that is what made sense to me.
 
Here is the map I found, if anyone is interested:
http://www.travelnet.is/isl/Journey/sv_al/index.html
 
Laurel