Apparently some of yall don't know shit about Finfolk and I will fix that
The finfolk are part of the Orkney Islands folklore. They are similar in nature to Selkies from Scottish folklore.
Finfolk in general are freakishly strong. The finmen are generally stronger than finwives. It is said they are able to row between Norway and Orkney within 7 strokes of the oar. Finmen are also extremely territorial and will kill any fisherman found fishing in his claim of the ocean. Though the finmen do not like Christian crosses and will avoid any boats with one on board. A finman's favorite activity is to cheat human fishermen out of their silver and their wives. Finman do not want a finwife. If they marry a finwife, they will be borderline abusive and send her away to work. Because they're ugly.
Finwives are also freakishly strong compared to a human. All finfolk are shapeshifters, and finwives make use of this to pretend to be beautiful mermaids and beautiful maidens walking along the shoreline to capture a husband. Why not just get a finman as a husband, you ask? Because a finwife who marries a finman is cursed to become an ugly hag. Nobody wants to be an ugly hag. So instead they marry a human husband and everybody is happy. Except for probably the human husband who gets enslaved and is unable to leave/live to tell the story.
I've seen it spelled both ways. Anyway this is the place where they live for at least their young life. This is where finfolk are made and their ancestral place. Finfolkhaem literally translates to "finfolk's home" so that makes sense. It is said to be immensely beautiful, with colorful corals and plants and seaweed surrounding it, and made of beautiful expansive crystal halls. It is said to never be dark here because of tiny bioluminescent sea creatures.
Literally "hidden land," this place is a paradise island that is always hidden from human view. The only way that a human would ever see it is if they become a husband or wife to a finfolk and are taken there. Some stories say it is hidden underwater. Other stories say it is hidden by a magical fog. Personally, I think it makes more sense if it's hidden underwater because it is known that finfolk grow weak if they are kept away from the ocean for too long.