Hyperborea

In Volume I of Poul Anderson's The Last Viking Trilogy, a Classical scholar in Constantinople introduces a claimant to the Norwegian throne as the King of Hyperborea!

In the concluding Chapter of Volume II, that claimant, who has by now been King of Norway for many years, leads an Arctic expedition in search of Hyperborea, Jotunheim or whatever else is to be found to the North. A learned Saracen had told him that the world was round. He might:

sail over the top to Vinland or Cathay;
find Hyperborea, believed by the Greeks to be " '...a land of ageless springtime, beyond the north wind...' " (Anderson, The Road Of The Sea Horse, New York, 1980, p. 247);
find the Norse Giant Land, the World Serpent, Ydhun's apples, the well of youth or unicorns in fields where flowers are stars.

What they do find is cold, darkness, fog, icebergs and a whale until they turn back to be well rewarded by their King but with a story that will be recorded only in "...some monkish chronicle..." - and in a Poul Anderson novel (p. 253).