Helcaraxë
Tolkein fans probably recognize that immediately -- for non-fans, Helcaraxë, "the Grinding Ice" is the path by which the Elves who we meet in LotR arrived in Middle Earth. There's much more to it, of course, but I'm using it here as shorthand for a postulate I've heard about: that the Clovis culture is partially descended from the Solutrean in Europe, which could have been brought to North America by people living in the niche now occupied by the Inuit.
In other words, coastwise navigation from northwestern Europe, except that the "coast" is the North Atlantic pack ice during a glacial maximum.
There's an episode of NOVA about it.