I think the last line "I have become a arial view of a coastal town that you once knew" is about loosing a friend or lover who now looks back on the memories of being with him, and that he is insignificant now to them now. "An arial view" implying that you only look at Fionn as a memory, because you do now actually walk round the town, don't experience being with him.
Beautiful song, from a very talented man.
I think the last line "I have become a arial view of a coastal town that you once knew" is about loosing a friend or lover who now looks back on the memories of being with him, and that he is insignificant now to them now. "An arial view" implying that you only look at Fionn as a memory, because you do now actually walk round the town, don't experience being with him.