A rather small (6×15 meters) cave at the foot of the Hellisfjall mountain, thats Landmannahellir in the Fjallabak area.

How to find Landmannahellir:

There is a gravel road of the very same name (Landmannahellir) off the F225 track, Central highlands, Iceland

GPS coordinates of Landmannahellir: 64.053098, -19.238535 Take me there!

Photos of the Landmannahellir cave: