The Green Cliffs of Glymur
This is one of the tallest waterfalls in Iceland and Europe. It is a bit of a hidden gem and requires about a two hour hike to get to this view, but well worth it in my opinion.
To get here you have to go through a pretty cool cave to enter the valley below the waterfall and then cross the river via a downed tree and hike a pretty steep trail. This photo does not do a good job of showing the scale and magnitude of this waterfall, so the best I can do is to point out the small white dots on the cliffs on the right side of this photo. Those are actually birds nesting in this very fertile and wet area.
The waterfall itself is over 640 feet tall from bottom to top and most of that is visible in this photo. If you are going to check this place out, I would recommend an App Called maps.me from the app store as it has all the trails clearly marked and came in handy a few times when we could not tell which way to go.