Hafragilsfoss (27m) is one of the three waterfalls of river Jokulsa a Fjollum.  It is located about two kilometres to the north of the mighty Dettifoss and well worth a short detour across an interesting crater in the landscape.  This crater is one of hundreds on the country's longest eruptive fissur (80 km).  On the western brink of the canyon, river Jokulsa eroded another crater, showing its guts.  The waterfall is known from the Saga literature (Grettis Saga), where it plays an interesting and a legendary role.