the story
1

Iceland is a beautiful island which landscape is a creation of  fire and ice. It is bubbling with hot geysirs. Inside the vulcanos there is a hidden world. A world with fire and hot water coming from the inside of the earth.

For Centuries there have been tribes of invisible creatures living in the hidden world of Iceland.

The only reason we  call it hidden is because humans cannot see it.

Those invisible creatures come in different sizes. Trolls are the same size as people. Giants are much bigger. Dwarfs much smaller.

All of those hidden people can be visible to humans only for 24, 30 days a year.

There is an old Icelandic folktale about a troll family. Gryla's family.