Keflavik stopover

7 hours in Iceland...
More and more I think I need to start a website on stopover birding. Specifically the art of seeing good birds with 2-5 hours spare at an airport.
I've been to Iceland before, pre-birding and got rapidly bored in a small, beautifu, astronomically expensive airport.  This was much better.  Plan A was to pack light hand luggage. Plan B was to check whether there was a left luggage at Keflavik. There was but it didn't open til over an hour after I found it... so I came to be trudging along the Keflavik access road with a foot of snow off the road, a scope in my backpack and an unintended laptop-containing holdall slung awkwardly over my shoulder.
Keflavik is not a perfect airport birding destination - cabs are expensive and bus routes only seem to go direct to Reykjavik, but it is only a 4 mile hike to the nearest coast and I had 5 hours to play with. Halfway down the access road, I saw my first bird - a merlin. The only small falcon in Iceland, so I didn't even have to try to hard to get close.
After that, it was a long time before I saw anything else.  I scoured the fields (not that patiently) for Ptarmigan, and saw lots of Starlings and a pair of possible flyover Snow Buntings as I walked through ?Njarvik?.  As the coast got closer, I heard and saw a dozen or so Greylag Geese flying away and started to hear gulls.
I decided to play it safe and not risk a bus to the northern tip of the SW peninsula and just to stay on the closest stretch of coast.  One big aim for the visit was the white-winged Gulls (Iceland and Glaucous), both of which turn up occasionally both in the UK and MD, but are mostly seen my people more patient and larophilic than I.  I managed to see both, for sure, although I saw more Iceland than Glaucous, the opposite of what I expected.
From there, I walked up and down the coast a little, then played it safe.  I didn't see Black Guillemot, King Eider, or Gyrfalcon (all rather unlikely, but possible, lifers) but I did see lots of Common Eider, Shags, Red-breasted Mergansers, Fulmars claiming on nesting territory on the cliffs (and flying around) and 5 other gulls.  Then I played it safe leaving for the airport early and lucked out when a nice Icelander stopped to give me a ride the rest of the way :-).