Askja is a large active volcanic caldera in the remote central highlands of Iceland, within the Dyngjufjoll mountains. The outer caldera covers about 50 square kilometres, and the Dyngjufjoll mountains rise to around 1,514 metres. It lies within Vatnajokull National Park, part of the wider Vatnajokull region, surrounded by the vast Odadahraun lava desert.
What and where Askja is
Askja sits in the middle of Iceland's highland interior, inside the Dyngjufjoll mountain system. It is an active volcanic caldera, and its setting is part of the larger volcanic landscape of Vatnajokull National Park.
The scale matters here. The outer caldera covers about 50 square kilometres, and the mountains around it rise to around 1,514 metres. Around Askja, the landscape opens into the Odadahraun lava desert.
Viti crater and its milky-blue bathing lake
Viti is a geothermal explosion crater with a milky-blue, mineral-rich lake. People bathe in it, and the water is typically around 20 to 30 degrees Celsius.
The approach into the crater is the part that needs attention. The descent to Viti is steep and loose, and it can become treacherous when wet. Bathing is at your own risk.
Oskjuvatn: Iceland's second-deepest lake
Oskjuvatn is the larger caldera lake beside Viti. It is about 220 metres deep and the second-deepest lake in Iceland.
The lake covers roughly 12 square kilometres. It is too cold for swimming. Oskjuvatn formed when the inner caldera collapsed during the 1875 eruption.
The catastrophic 1875 eruption
A major eruption began on 28 March 1875. It was followed by a devastating rhyolitic explosion on 29 March 1875.
The effects reached far beyond Askja itself. Ash at least 1 cm thick covered about 5,000 square kilometres, poisoning land and killing livestock in eastern Iceland.
Where Apollo astronauts trained for the Moon
NASA used Askja to train Apollo astronauts in 1965 and 1967 because the terrain resembles the lunar surface. Neil Armstrong was among the astronauts who trained in the Askja area.
Visiting Askja: F-roads, seasons, and highland tours
Askja is reached only in summer by 4x4 on highland F-roads, typically open late June through early September. Access is via the F905 to F910 route, or the shorter, rougher F88 past Herdubreid, which crosses unbridged rivers.
From the Vikraborgir car park, it is about a 2.5 km walk each way to Viti. Road opening dates change year to year, so check road.is and safetravel.is before setting out.
For a guided approach, an Askja and Víti super-jeep tour handles the highland roads. You can also compare the wider set of highlands tours.
Check before setting out
For the latest access information around Askja Caldera Iceland: What to Know, consult Iceland road conditions before you travel.
