Fagrifoss is out in the middle of practically nowhere on the southern part of the island except that it's just steps from the Ring Road, which is the main highway that encircles the island. Even so, the waterfall can't be seen from the highway, which explains why I would be willing to bet on the accuracy of the thread title.
I would love to spend hours walking up this little stream, as I'm sure there are other beautiful scenes along the way. Unfortunately, I didn't have time to do that. Even if I had had the time, I don't know about laws and possible restrictions about walking on private land in Iceland.