Dettifoss Waterfall is the most powerful waterfall in Europe in terms of water volume. It is certainly an impressive sight. The average water flow is close to 200 cubic meters per second but it decreases during winter and grows considerably in summer. It is about 100 meters wide, plunges down 44 meters into Jökulsárgljúfur Canyon and can be approached by visitors from both sides. Witnessing this awesome sight and hearing the roaring sound, you can´t help but to feel humble. The waterfall is in the glacial river Jökulsá á Fjöllum that takes its source in Vatnajökull glacier, the largest icefield in Europe, covering approximately 8500 sq km. The glacial river Jökulsá á Fjöllum is meltwater off the glacier. Dettifoss is accessible from both sides of the river. The west side is accessible by a paved road number 862 more or less all year round, while the east side is only accessible by a rough gravel road number 864 during the middle of summer. This road is usually passable and open to traffic from early June until early October. From the eastern bank there is an extremely rough footpath from the car park that leads down into the canyon and to the waterfall so great care should be taking while walking there. The canyon is in Vatnajökull National Park, the largest National Park in Iceland. There are two mor impressive waterfall in the same canyon. Selfoss is a short distance (about 1 km) south of Dettifoss. It is about 11 meters high and about 100 meters wide. The other is Hafragilsfoss, about 2,5 km downstream from Dettifoss. Hafragilsfoss is about 30 meters high and about 90 meters wide. Visitors are warned to be extremely carful walking on the slippery and rocky grounds near all the falls. Dettifoss has been featured in the opening scene of the science fiction movie Prometheus that many people have seen.