An online buddy from years ago said his Scandinavian ancestors' business records showed that during the medieval warming period, they sailed the thawed Arctic Ocean all the way to the Bering Strait, returning the following year, for trade, but obviously they were explorers looking to drum up some business. Of course, I've always kinda wondered about this story...
Don’t wonder too much. At least one site on the north coast of Canada, as I recall, at least halfway to the Bering Strait, had Viking artifacts.
Here’s a web page that will interest you. Iron-making in the Viking age.
http://www.hurstwic.org/history/articles/manufacturing/text/bog_iron.htm