Odadahraun is the most extensive lava field in Iceland, with a total area of around 4-6000 km² (definitions vary), consisting of relatively young and rough lava. It lies north of Vatnajokull and at its northern border are mountains Blafjall and Sellandafjall. Its boundaries are further marked by the great glacier rivers Skjalfandafljot to the west and Jokulsa a Fjollum to the east.
The area is dry and there is little as no vegetation. Sand storms there can also be very strong. The area is considered a part of Vatnajokull National Park. The only road through Odadahraun that is accessible by car is Gaesavatnaleid.
The area is strong in volcanic activity, the most famous volcano being Askja in the Dyngjufjoll mountain range. Further north of Odadahraun more lava stretches all the way to the sea with some eruptions having occurred in the sea. Here you find the volcano Krafla and the Gjastykki geothermal area. The impressive mountains Trolladyngja and Herdubreid are found further south.
Herdubreid is the highest mountain of the area, a tuya mountain, 1682 meters high. Near Herdubreid is the oasis Herdubreidarlindir, a popular stop for travelesr that offers a camping ground and several hiking trails.
This area, along with the Sprengisandur sand field further west, is known for hosting outlaws in former times, the most famous being Fjalla-Eyvindur and his wife Halla and their fellow outlaw Arnes. Their story, already legendary, was dramatized in playwright Johann Sigurjonsson’s play Fjalla-Eyvindur, later made into the Swedish film Bjerg-Ejvind och hans hustru (e. title ‘The Otlaw and his Wife') by Victor Sjöström.