I'd go for Iceland - looks fairly smallish, eye dark, bill not very stout, and (although not at the best viewing angle) the primaries look very long. Unusually pale basal section of the bill, but I think not out of the range of variation for 1st summer.
This gull has traveled through several forums and the verdict seems to be Iceland.
Rather worn and bleached and therefore difficult to age on plumage features. However, the bil pattern and the fact that the gull is moulting - to, presumable, second winter is imo a realistic suggestion. The bil pattern as billsize is variable - have a look at this presumably 3cy (second winter/summer) and notice a paler eye than the subject one, but with a similar billtip pattern but a different colour at the base.
For fun, compare with this kumlieni taken at approx. same time of year:
I think itīs a 2cy Iceland moulting to second winter (but canīt exclude a kumlieni from these images - heavy bill).
Of course the possibilitys of a barrovianus Glaucous Gull is to be considered. However some female hyperboreus are small-billed and a specific racial identity as a barrovianus in a plumage like the subject bird would be impossible. Probably in adults , where the upperpart s tone would stand out side by side, as darker in barrovianus compared to hyperboreus, although there seems to be a certain overlap in this feature.
The impression of a large eye in the subject gull would indicate - together with range - an Iceland better.
I can not confirm that all these are barrovianus:
Note the small eye:
Hmm personally im going to say Iceland. I think at first glance the amount of pink at the base of the bill is deceiving. Looking at the long primaries, gentle expression and generally slender 'jizz' im going to punt for Iceland Tis a funny one though...
Leucistic Herring Gull has been suggested:
Not a bad call??