Dettifoss is situated on the Jokulsa a Fjollum river, which flows from the Vatnajokull glacier and collects water from a large area in Northeast Iceland. The fall is 100 metres wide and have a drop of 45 metres down to the Jokulsargljufur canyon.
Since it's partly buried in the canyon, Dettifoss is overlooked by cliffs on both sides. From the west, the full face of the waterfall can be seen, and a short walk places you on top of the lava dam and fault line, that are responsible for the waterfall's location. The river water is almost always dark with sediment, in contrast with the white rapids and spray. During floods the river and the falls are often virtually black with sediment and debris.
The mighty Dettifoss is accompanied by two other substantial waterfalls. Selfoss is a few kilometers south and Hafragilsfoss is a few kilometers north. It is possible to reach the waterfalls from both sides of the glacial river Jokulsa, but one has to be careful when traversing the rugged terrain on foot. On the west bank there are no facilities and the view on the waterfall is somewhat hindered by the waterfall's spray. On the east bank there is an information panel maintained by the staff of Vatnajokull National Park and a maintained track to the best viewpoints.
Dettifoss appeared in the opening scenes of the 2012 science-fiction film Prometheus. Since then, some people have been calling it "the Prometheus Waterfall".