Bombus hypnorum Linnaeus, 1758, Søborg, Denmark, 20 June 2015
Approaching nest hole.
This small bumblebee is evidently pretty new to Iceland, and 'found mainly in urban areas'...
That fits here: a fair sized town with a number of geothermal heated greenhouses. Most of these are used to cultivate flowers.
Got no pix; but I'm pretty sure I also saw one at Lake Myvatn-- a place mainly famous for ducks, fish and clouds of tiny dipterans.