Askja Caldera
Askja is a large active volcano and caldera complex in the central highlands of Iceland, sitting within Vatnajökull National Park at around 1,100 metres elevation. The name means box or casket in Icelandic, a reference to the nested structure of calderas within the surrounding Dyngjufjöll mountains. At its centre lies Öskjuvatn, Iceland's deepest lake at 217 metres, formed after a catastrophic eruption in 1875 that sent ash across eastern Iceland and as far as mainland Europe. Beside it sits Víti, a smaller explosion crater filled with milky-blue geothermal water at around 25 degrees Celsius, into which bathing is sometimes permitted subject to ranger conditions on the day. Before the Apollo moon landings, NASA used the lunar-like landscape around Askja to train astronauts for surface operations.
Iceland's Most Remote Major Volcano, Where Apollo Astronauts Trained for the Moon and Two Scientists Vanished Without Trace
Askja's main caldera formed over 10,000 years ago when a magma chamber collapsed beneath the Dyngjufjöll mountains at the end of the last ice age. A further major eruption in 1875, Iceland's largest in modern recorded history, created a smaller nested caldera inside the first, now filled by Öskjuvatn lake. The ash cloud from that eruption spread across northern Europe, destroying crops and pastureland in eastern Iceland and causing a significant emigration of Icelanders to North America in the years that followed. The lake that filled the new caldera is Iceland's deepest at 217 metres and sits 50 metres below the surrounding caldera floor, giving it an enclosed, otherworldly quality. The lake is frozen for most of the year and even in midsummer retains patches of ice. A 2014 study confirmed that a landslide into the lake in 1907 likely generated a wave over 30 metres high, which is thought to explain the disappearance that year of two German scientists, Walter von Knebel and Max Rudloff, who were conducting research on the lake and were never seen again.
Víti, meaning Hell, is a smaller explosion crater on the northeast shore of Öskjuvatn, distinct from a larger crater also called Víti near Krafla in North Iceland. The Askja Víti is filled with geothermal water at around 25 degrees Celsius, coloured a striking milky blue-green by dissolved minerals. Bathing in the crater is one of the more surreal experiences available in Iceland, swimming in volcanic water at 1,100 metres elevation in the middle of a lunar highland landscape, but it is subject to ranger permission and conditions on the day and should never be assumed available. The path into the crater is steep and can be very slippery when wet. NASA geologists brought Apollo program astronauts to the Askja area in the 1960s to acclimatise them to terrain that resembled the lunar surface, a connection that gives the landscape a particular cultural resonance for visitors who know it.
Askja is accessible only by F-roads, requiring a 4WD vehicle, and is open roughly from late June to early October depending on snow conditions. The primary route is the F88 from the Ring Road north of Mývatn, a drive of around two to three hours each way from the highway. Guided super jeep tours depart from Mývatn and Akureyri and are the most practical option for most visitors. The highland shelter at Dreki near the caldera provides basic facilities. Conditions at this elevation can change rapidly: visitors should carry extra clothing, food, and water and check road conditions at road.is before departure. Askja is within Vatnajökull National Park and is free to enter.
