Your life can depend on a cairn.
To the east the road to the south goes around Strutsfoss (the falls in the distance) and over the glacier. To the west …
… the highway goes up over the glacier. The cairn marks this bridge:
You’ll be needing it.
Hang on!
Did you wonder where it was? It’s in þingvellir. 
If you don’t walk it, it will disappear. That would be like letting the ancient romanesque cathedrals of Europe fall into ruins and be carted away as bricks. That’s what you’re looking at, so get on out there!
They’re all winding when wended on foot.
Hafragillsfoss
That’s because they wind you in and, wound up, you look behind and what is there? Only the wind. And when you turn you step into the wind in that direction too.
A Farm in Iceland 