Dettifoss Waterfall

The water is greyish white, not clear. The Jökulsá á Fjöllum carries sediment straight off the Vatnajökull glacier, and the colour never washes out.

The river drops 44 metres here over a lip 100 metres wide, at an average 193 cubic metres per second. That is second in Iceland by volume after Urriðafoss, and reputed to be the second most powerful waterfall in Europe after the Rhine Falls. You can hear it long before the canyon opens up.

Three separate paths lead to different vantage points, on ground of bare volcanic rock. Barriers hold visitors back from the edge, so the scale registers more than the force. When the sun catches the spray, a half-circle rainbow stands over the canyon. Selfoss lies on the same walk from the car park.

• Toilets: free on both banks — a pit toilet on the west, a public toilet on the east. No drinking water on site.
• Snow: while it lies, sections of path and platform are broken and diversions make the walk longer.
• Barriers keep visitors well back from the water, so you see the scale rather than feel the force.
• A café and a souvenir shop operate near the falls, selling clothing and knitted sweaters.
• The west side is the busier of the two, and it is the side with the view platform.

No bus comes here, so the last stretch is by car. Route 862 serves the west bank and is tarmac, laid in 2011. Route 864 serves the east bank; it is gravel and usually passable in summer only. Both sides have a car park, and from the west car park it is an easy walk to Dettifoss and to Selfoss. The west bank has a maintained hiking path and a view platform, the east bank a trail and a national park information panel.

Better: summer, if you want the east bank — Route 864 is normally passable only then.

Avoid: the period when snow is still lying, because paths and platforms are broken and diversions lengthen the walk.

The west approach on Route 862 holds up through most of the year, so the falls stay reachable outside summer if you come from that side. Sun on the spray is what produces the half-circle rainbow over the canyon.