Since Vikings settled in Iceland it would fit the game nicely. I went there a few years ago and was blown away by the bizarre yet beautiful landscape- completely alien to anything I had seen before. Huge waterfalls, barren rocky wastes, crazy rock formations and plateaus, glaciers and volcanoes, huge rivers, stormy shores, geothermal stuff going on everywhere… The scenery was huge in a way that made you feel small- everything about it was powerful and awe inspiring. Not sure if true, but apparently Vikings thought they had found the land of the gods because of this?
Look up images of Iceland- it would really fit the atmosphere well of a barren wilderness Viking purgatory. It could lead to the world having a bit more verticality too, since right now the world feels a bit flat except for mountains. You could even have geothermal lagoons give you the warm comfort bonus and give volcanic rock special crafting uses, or have a mechanic around waterfalls. It would be a cool type of landscape to try and recreate too, and I realize that ashlands might already have some icelandic characteristics. Off the top of my head the only other game I've seen make Iceland is Death Stranding, and even then it didn't communicate the variety of scenery the country has irl.