Dettifoss est la cascade la plus puissante d'Islande. Il est situé dans le parc national de Jokulsargljufur le nord-est de l'Islande sur la rivière Jokulsa a Fjollum.
Dettifoss is a spectacular waterfall 45 meters high and 100 meters wide located in a completely deserted lunar landscape and boasts the title of waterfall with the largest water flow in Europe in the heart of the desert area of north-eastern Iceland