On the way to Dettifoss from Asbyrgi, there is a small single lane gravel road heading west off of 864. It was rather interesting driving there in my RV but I made it. I was promptly greeted by 35km/h winds which made for a tricky walk down the slope from the parking lot to the viewing area of Hafragilsfoss. With the strong winds I did not want to take the time to search for a path down for a closer view. You can see mist rising from Dettifoss upstream.