Fjallsárlón is a glacial lagoon, located on the southern end of Iceland's huge Vatnajökull glacier. The glacier extends all the way to the edge of the lagoon where icebergs break away and drop into the water below.
Whilst we had seen many images of 'blue ice' - apparently an effect due to air bubbles being squeezed out by the high pressure within the glacier - we had never actually encountered real examples.
We loved just standing there and watching the icebergs floating along very slowly. Every now and then you could hear the rumble of another piece breaking off the glacier.
The photos above were taken in the late afternoon. However, we were so fascinated by the scenery that we returned the next morning. The next two shots are from the second visit.
The different light conditions provided a clearer view of the glacier itself.
A few kilometres further east is another glacial lagoon, called Jökulsárlón. It receives many more visitors than Fjallsárlón, but I would not say that it is more spectacular. One additional attraction, however, is that there is a footpath from which you can watch a continual stream of icebergs floating towards the sea.
Small pieces of ice often end up on the black sand beach nearby, earning it the nickname of 'Diamond Beach'.
There are free car parks, easily accessible from the R1 (the 'Ring Road'), at both lagoons.
In case you are wondering how cold it was: we were actually in shirt-sleeves, as July 2021—when we were here—saw temperatures in the mid to high 20s (centigrade) on quite a few days.