There is a nice walk you can do in Keflavík town if you want to kill a couple of hours before your flight. It runs along the cliffs between Keflavík and Garður and I think it would take around 2 hours (more if you stop a lot) to do the whole walk out and back. We did most of it in 90 minutes without much stopping.
The walk is pretty flat, BUT is along rocks the whole way so you need proper walking shoes and the rocks will be slippery if it has been wet. A path has been made from the rocks that are lying all around, and it is easy to see most of the time.
You get some pretty spectacular ocean views along the way.
In August, there was still a lot in bloom and you could see that there would have been many lupins earlier in the year.
It was also interesting to see the porous lava rocks, and the way that in places they become very large and smooth as they run off down to the sea.
I was impressed at how much work it would have taken to actually make this path. Although the material is right there it would have been a big job to turn the random rocks into something relatively flat and walkable, and to make so many benches along the way.
We were lucky that the weather was relatively calm and dry, it wouldn’t have been a very nice walk the day before!
You can start this walk from Bakkavegur, the path is at the end of the road.