The next day we drove from lake Mývatn to the Askja vulcano in the higlands. Because of high water and the required river crossing we had to take a long route (F905 and F910), but everything went fine. This trip tool basically the entire day, but it was well worth it. Both the trip to and from the Askja itself were beautiful and gave a view on the big table mountain Herðubreið.
On the road towards Askja a trooper informed us that it's also possible to go to the beginning of a river that is appearing out of nowhere from the ground.
Further offroad there was a possibility to visit a new Lavafield (Holuhraun), which looks much darker then old lava as you can see on the picture below. We didn't dare to get close, because we had to cross another river and we couldn't estimate how deep it was. There was a superjeep crossing and it seems to be quite deep at a certain spot, so we decided not to take the risk to get stuck as it was already at the end of the day.