A cave below Skutafoss creates a very nice framing for the waterfall.
This is a really nice waterfall. Possibly a bit ordinary by Icelandic standards, but there are some interesting compositions possible and this one from a cave is the most unusual in my opinion.
Photo tips: A bit tricky to capture, since even my 10-24mm (15mm full-frame) wasn't wide enough. So I opted for 3 frames panorama later stitched in Lightroom, which worked pretty well.
Getting there: Just turn off the main road to a small dirt track and park there. A good 4WD vehicle could easily get right next to Skútafoss, but I'd say it's better to walk the last few hundreds meters and enjoy the scenery.
Since it's easily accessible, you can expect other people during the day.