Askja is a 50 km2 caldera in the Dyngjufjoll mountains. The mountains emerged in eruptions under an Ice Age glacier cap. Askja itself was formed, for the most part, at the end of the Ice Age in a major ash eruption which caused the roof of the magma chamber at the heart of the central volcano to subside.
Askja is a part of Vatnajökull National Park.
The caldera contains several volcanoes, including Víti (explosive volcanic crater). Water has accumulated in the crater, its temperature is variable - it is around 30°C on average. Víti is a popular bathing site, but if you intend taking a dip, please be aware that the sloping path is very slippery in wet weather.
The road to Askja goes from road 1 to road 901 and onto mountain road F905. Onward to F910 to Drekagil. On this route there are two fords to cross, usually small. From Drekagil goes mountain road F894 (8 km) to the car park at Vikraborgir.
Another option is to go from road 1 to mountain road F88 via Herðubreiðarlindir to Drekagil. On this road ther are fords on the rivers Grafarlandsá and Lindá that need to be crossed. The fords can be difficult or even impassable for small jeeps.