Flowing from the glacier Vatnajokull, Dettifoss is known to be the most powerful waterfall in Europe.
There are two ways to see Dettifoss - from the west side of the river and the east side. The WEST side is more easily accessible and allows all types of vehicles. You can navigate to the West side parking lot with this link.
To view the waterfall from the EAST side, you will be driving on mountain road, 864. This may as well be an F-Road and therefore a 4x4 vehicle is highly recommended. There are no river crossings to get to Dettifoss East Side but a vehicle with a high clearance is necessary.
The roads to both sides of the river become impassible in the winter so, especially before heading to the east side, be sure to check road conditions and closures at road.is.
If you want to play it safe and be in a well-equipped, photogenic car, then you should rent an old-school Land Rover Defender from www.isak.is. Use the code "gunnar" for renting your Defender on a special price.