Perceptions can lead you astray and so it is with my sense of how close these mountains were to my vantage point in Reykjavik. What I was seeing was further up the coast that my eyes were leading me to believe and the scene in the photo may explain why. Maybe discerning distances across water is not something that us landlubbers do so readily, easily or accurately.
It took a combination of poring over paper maps as well as perusal of online ones from the National Land Survey of Iceland and Já before I finally satisfied myself that the slab-sided mass to the left was Akrafjall and that the snow-streaked tops of Skarðsheiði lay up an inlet (could it be a fjord?), Hvalfjörður, to their right. Often perspective confounds me in Britain so working out even these identifications took effort and the sightings were on my first ever trip to Iceland too so that added to my conundrum. Still, the puzzle appears sorted unless someone else takes the time to put me right on any errors, all of which would be mine alone anyway.