Dettifoss is a waterfall in Vatnajökull National Park in Northeast Iceland, and is reputed to be the most powerful waterfall in Europe.
It is situated on the Jökulsá á Fjöllum river, which flows from the Vatnajökull glacier and collects water from a large area in Northeast Iceland. The falls are 100 m wide and have a drop of 45 m down to the Jökulsárgljúfur canyon. It is the largest waterfall in Europe in terms of volume discharge, having an average water flow of 193 m3/s.