Eldgja, or "The Fire Fissure”, is 40 km long and stretches from the glacier Myrdalsjokull to the low mountain Gjatindur and beyond it further northeast. It is a unique natural phenomenon, which was created during a tremendous eruption around the year 900. In places it is 600 m wide and very deep.

The lava field's area, created by this eruption, is close to 700 km˛, which makes it the largest historical lava field of the country. There are two main accesses to the fissure, one from its depression and one from the eastern rim. Both lead to the waterfall Ofaerufoss, which natural stone arch collapsed in 1993. The view from the top of the aforementioned Gjatindur is breathtaking on a fine day. The buses of Kynnisferdir include The Fire Fissure in their schedule every day during summer.

Landmannalaugar 41 km <Eldgja> Kirkjubaejarklaustur 79 km.