Jökulsá á Fjöllum
 Jökulsá á Fjöllum is the second longest river in Iceland (206 km). Its source is the Vatnajökull glacier. It flows into the Greenland Sea. Jökulsá á Fjöllum streams over the waterfalls Selfoss Dettifoss and Hafragilsfoss the second of which is the most powerful waterfall in Europe and through the canyon at Jökulsárgljúfur National Park which was formed by the explosion of a volcano situated directly beneath the river. Consequently the course of the river changed to fit the mountains.