I think Manitas has it right, it's not about the Cliffs of Moher, it's from where you can see from over to Kilkee &tc. It might have been Dúnín, or Duneen, or Duinín, there is a Dunmor nearby, so Duneen should be thereabouts. I certainly don't think it has anything to do with Duneen Beach down near Clonakilty, you's have to look over a lot of mountains as the song says, but the song does say 'look over the mountains'