The Dimmuborgir (meaning dark cities, forts, or castles) Lava Field, located in the heart of the Mývatn Geothermal Area, is about 100 kilometers east of Akureyri.

The Dimmuborgir area, as the name suggests, is an unusually shaped lava field consisting of peculiar volcanic caves and rock formations. These dramatic structures are a favorite stop for tourists.

This natural phenomenon dates back some 2300 years to a massive eruption in a nearby crater. The lava seems to have flowed over a small lake that once existed; water below the lava was trapped and boiled, and the steam rose, forming lava pillars from drainpipes up to several meters in diameter. As the lava continued flowing toward the lower ground in the Mývatn Lake area, the top crust collapsed, leaving behind hollow pillars of solidified lava. The lake must have been at least 10 meters deep, as estimated by the tallest structures still standing.