Thanks, I'd not heard the story about C in Ireland. Columbus went to Iceland as part of his research, his visit to Ireland may be why. If memory serves, the King and Queen of Spain had already turned him down, and he was packing to leave, to make his pitch somewhere else, when the Moors were finally expelled (last ruler Abdul Abdullah Boabdil; the anecdote was, he took a long look back at his former capital and wept, and his mother said, "don't weep like a woman for that which you could not defend like a man." There's nothing like a mother's love. ;^)
Anyway, the Reconquest was done, so the monarchs changed their minds and bankrolled Columbus. For his part, Columbus had studied the crap out of the whole thing, and accepted the view going back to ancient Greece that the known landmasses were all that existed, but the reports of the nearby landmasses to the west caused him to reject the estimate (also going back to ancient Greece) of the circumference of the Earth. After he made landfall in what turned out to be the Americas, he really thought he'd shrunk the Earth.
I used to know a guy online who had deep roots in Scandinavia; he claimed ancestors who, during the medieval warming period, had taken advantage of the 24 hour days of Arctic Ocean summer to trade with eastern Asia. That's pretty interesting, though anecdotal.
I was not sure if I remembered Ireland or Iceland, so Googled “Did Columbus travel to Ireland to research his travels.” Sure enough the first article listed was about Columbus taking an Irishman with him who had told of his own travels to land in the West. The second article is about a colony of Irish in the Carolinas that predated Columbus’ voyages. Farley was right!