Fardagafoss is actually a pair of attractive waterfalls just upslope from the town of Egilsstađir. The first waterfall has an attractive rectangular drop that you can see from its side. The upper waterfall is actually a two-tiered cascade. Personally, I think the lower waterfall is the more interesting of the two. You can find the trailhead for the falls as you drive the mountain pass road connecting Egilsstađir and Seyđisfjörđur (roughly 5km from Egilsstađir). You get good views of Egilsstađir as you turn around and look back towards Lagarfljót.