Gljufurarfoss (Gljúfurárfoss; I think is pronounced "GLYOO-fir-owr-foss") was a waterfall where I had to be content with obstructed views due to its rather hidden position behind a mini narrow slot canyon. I actually tried to wade my way into the misty confines of the waterfall's base, but the water was so cold that my feet and ankles couldn't handle it (they were both feeling both painful and numb [if that makes any sense]). I probably barely lasted a dozen steps before I had to chicken out.
I believe this waterfall is translated to mean "canyon river waterfall," but I've also seen people refer to this as the "spooky" waterfall.
Due to its proximity to Seljalandsfoss, it's often overlooked (it looked like tour buses didn't stop long enough to allow you to walk to this waterfall and back). So it's fairly easy to have a peaceful experience at the falls if you're content to just see glimpses of it from closer to the road (but you do have to get here individually).
Directions: Drive towards Seljalandsfoss, but then continue another 800m to the smaller car park for Gljufurarfoss.