Heading along the north edge of the Vatnajukoll Glacier, which covers most of southeast Iceland, the Jokulsa a Fjollum River flows northward to enter the North Atlantic via a broad delta on Oxafjorour Bay. Covering 206 km, it is the second longest river in Iceland but is easily the largest with respect to its vast watershed and annual flow.
This flow was especially great at the end of the Pleistocene as Iceland's glaciers were beginning to melt. During that time, about 10,000 years ago, the River cut a deep canyon in the volcanic plains of northeast Iceland; now protected within Vatnajokull National Park, the Jokulsargljufur Canyon is the largest and most spectacular chasm on the island and harbors a series of magnificent waterfalls. The second of these, Dettifoss, is among the largest falls in all of Europe; though not as easily accessible as Gullfoss and Godafoss, Iceland's other famous waterfalls, the sight (and sound) of this powerful falls and the grandeur of the canyon in which it lies, are well worth the effort.
During the peak of the River's flow, some 8000-9000 years ago, volcanic eruptions occurred near and along the canyon walls, producing spectacular basalt formations in the vicinity of Dettifoss. Trails on the west side of the canyon (north of Dettifoss and south of the National Park visitor center in Asbyrgi) take you among these volcanic monoliths and provide a unique perspective on the various natural forces that produced the landscape of Iceland.
