Askja, Iceland: Caldera, Víti Crater, and Travel Guide

Askja is an active volcanic caldera in Iceland's central Highlands, located within the Dyngjufjöll mountains north of the Vatnajökull glacier. The caldera covers about 50 km² (19 sq mi) and contains two of Iceland's most distinctive volcanic features: Öskjuvatn, the inner caldera lake formed by the catastrophic 1875 eruption, and Víti, a small geothermal crater with milky-blue water. 

Reaching Askja takes a full day and requires a 4x4 on rough Highland gravel roads, typically open from late June to early September. The terrain is one of the most barren and otherworldly volcanic landscapes in Iceland, used by NASA to train Apollo astronauts in the 1960s. Most travelers visit on a guided day tour or self-drive on the F-roads.

Askja is a 50 km² (19 sq mi) volcanic caldera or volcanic depression in the central Highlands of Iceland, north of the Vatnajökull glacier and within Vatnajökull National Park.

The name Askja comes from the Old Norse word for a box or casket, a reference to the way the caldera nests inside the surrounding Dyngjufjöll mountain range. The Dyngjufjöll themselves emerged through eruptions under an Ice Age glacier cap, and Askja formed later, when major ash eruptions caused the roof of an underlying magma chamber to collapse.

The caldera is the central part of an active volcanic system that includes a fissure swarm extending about 190 km (118 miles) across northern Iceland. The central volcano itself is roughly 20 km (12 miles) in diameter, with a smaller main caldera nested inside it and an even smaller inner caldera, formed during the 1875 eruption, now holding the lake Öskjuvatn.

There are no towns, fuel stations, or services within reach of the caldera. The only road access is on Highland F-roads that close from October through late June each year.

The terrain around Askja is almost entirely without vegetation, with open volcanic deserts and lava fields stretching to the horizon. Standing on the rim of the caldera gives a clear view of both Öskjuvatn and Víti directly beside it, with the milky-blue water of the smaller crater framed against the black volcanic ground.

Askja also rewards travelers who want a real Highland experience. The drive in is long and slow, the landscape changes dramatically along the way, and there are no crowds of the kind found at the Golden Circle or the South Coast. For self-drivers with the right vehicle and preparation, the caldera is one of the most rewarding single destinations in Iceland. 

The Lake Mývatn area in North Iceland is where the F-roads to Askja begin and where most guided day tours depart.

Askja is in Iceland's central Highlands, within Vatnajökull National Park, about 100 km (62 miles) southeast of Lake Mývatn and roughly 230 km (143 miles) east of Akureyri.

The caldera is north of the Vatnajökull glacier, within the Dyngjufjöll mountain range, in a remote section of the central Highlands with no towns, fuel stations, or services nearby. Vatnajökull National Park is Iceland's largest protected area, covering about 14% of the country's landmass.

GPS coordinates: 65.0111° N, 16.7485° W.

Reaching Askja requires a 4x4 vehicle on Highland F-roads, typically open from late June to early September. Most travelers base from Lake Mývatn, the closest practical starting point, and either self-drive or join a guided day tour.

F-roads are unpaved gravel mountain roads with rough surfaces, river crossings, and no services. Check road and weather conditions at road.is and safetravel.is before setting out, and never attempt the route in a standard 2WD car. Most rental agreements prohibit driving rental cars on F-roads, so travelers without a Highland-rated 4x4 should join a guided tour.

The drive from Reykjavík to Askja takes 7 to 10 hours one way and is usually split into two days. Take the Ring Road (Route 1) north through Borgarnes and Akureyri to the Lake Mývatn area, a drive of about 6 to 7 hours on paved roads. From Mývatn, continue on F-roads to the caldera as described below.

Most self-drivers stay overnight at Mývatn before attempting the F-road section. Doing the full Reykjavík to Askja drive in a single day is possible but demanding and leaves little time at the caldera itself.

From Mývatn, two F-road routes lead to the Askja parking area at Vikraborgir. The drive takes 4 to 6 hours one way depending on conditions and route choice.

Route 1: F905 to F910 to F894 (longer, easier). The most accessible route, with fewer significant river crossings and manageable in a standard 4x4. Take Route 1 west from Mývatn, then Route 901 onto F905 across the Highlands. Continue on F910 to Drekagil and the Dreki Mountain Hut, then follow F894 for about 8 km (5 miles) to the Askja parking area at Vikraborgir.

Route 2: F88 (shorter, harder). The F88 (Öskjuleið) is more direct but includes two significant river crossings where water levels vary daily. This route is not suitable for small or low-clearance 4x4 vehicles. From Mývatn, take Route 1 east, then turn onto the F88. The drive passes through Herðubreiðarlindir, an oasis at the foot of Herðubreið mountain, and reaches Drekagil in about 2 to 3 hours, with the final stretch on F894 to Vikraborgir parking.

Travelers approaching from East Iceland can reach Askja via F910 or F88. The route is longer than from Mývatn and still requires a 4x4 with good clearance. Egilsstaðir is also a useful base for combining Askja with the eastern fjords on a longer Highland-and-East-Iceland trip.

For most travelers, a guided day tour from Lake Mývatn is the easiest and safest way to reach Askja. Tours handle the F-road driving, river crossings, and route conditions, leaving the visitor to focus on the caldera. Tours typically run from late June through early September.

The Askja caldera covers about 50 km² (19 sq mi) and contains Öskjuvatn, an 11 km² (4.2 sq mi) lake formed during the catastrophic 1875 eruption and reaching about 217 m (712 ft) deep, the second-deepest lake in Iceland.

The caldera structure is layered. The outer caldera, formed by major eruptions and the collapse of an underlying magma chamber, is roughly 50 km² in area. Inside it sits a smaller main summit caldera about 8 km (5 miles) across, and within that, an even smaller inner caldera created by the 1875 eruption now holds Öskjuvatn.

Öskjuvatn itself is distinct from a typical crater lake: rather than filling a vent, it occupies the inner caldera that collapsed during the 1875 event. By depth, only the Jökulsárlón glacial lagoon at about 284 m (932 ft) is deeper. By surface area, Öskjuvatn is much smaller than Iceland's largest lakes (Þingvallavatn covers 84 km²), but it is one of the deepest standing bodies of water in the country, and its dark, intensely turquoise water is one of the most photographed sights at Askja.

Víti is a small geothermal crater inside the Askja caldera, formed during the 1875 eruption and known for its milky-blue, mineral-rich water with temperatures typically between 20°C and 30°C (68°F to 86°F).

The crater sits a short walk from the Vikraborgir parking area, reached by a footpath that climbs over the caldera rim and then descends a steep, loose slope to the water. Víti's name is the Icelandic word for hell, a reference to its violent eruptive origin and the steaming, mineral-stained water inside.

Some visitors swim in Víti during warmer months, when the water temperature is most comfortable. Conditions vary, the path down is steep and slippery especially in wet weather, and the surface temperature can be deceptive: warm sections sit alongside cooler ones, and the bottom is muddy. Check current conditions before planning a swim, and never enter the water if you are unsure.

Askja last erupted in 1961, but its most important historical eruption happened in 1875. That explosive event reshaped the volcano, formed the inner caldera that now holds Öskjuvatn lake, and spread ash across eastern Iceland.

Before 1875, Askja was little known outside the Icelandic Highlands. That changed on March 28, 1875, when a powerful eruption sent rhyolitic ash high into the atmosphere. About 5,000 km² (1,930 sq mi) of land received an ash layer at least 1 cm (0.39 in) thick, damaging farmland and poisoning grazing areas across eastern Iceland. Winds carried ash as far as Norway and Sweden.

The impact was severe. Contemporary records suggest Iceland lost roughly 2% of its sheep and 6.2% of its cattle after the eruption, mostly in the eastern districts where ashfall was heaviest. The damage contributed to a wave of emigration to North America in the years that followed.

Askja’s most recent eruption, in 1961, was much smaller. It produced about 0.1 km³ (0.024 cubic miles) of basalt lava on the northern caldera floor. This lava field is now known as Vikrahraun, and visitors cross part of it on the walk between the Askja parking area and Víti crater.

The most recent major volcanic activity in the wider Askja area was the 2014–2015 Bárðarbunga fissure eruption, which created the Holuhraun lava field about 15 km (9.3 mi) south of the caldera. Holuhraun is Iceland’s largest lava field from any eruption since the 1783 Laki eruption, and Arctic Adventures’ main Askja day tour includes a stop there.

Askja remains an active volcanic system. The Icelandic Met Office monitors it continuously through seismic and GPS measurements. Recent years have shown ground deformation and small earthquakes consistent with magma movement at depth, but no eruption is imminent. The system's behavior is followed closely by Icelandic scientists and is one of the most closely watched in the country.

On July 10, 1907, two German scientists, Walter von Knebel and the painter Max Rudloff, disappeared while rowing on Öskjuvatn. Their bodies were never found, and the Askja case is one of the best-known unsolved disappearances in Icelandic history.

Knebel, a geologist, had come to Askja with fellow scientist Hans Spethmann and Rudloff, a painter, to study the caldera. Knebel and Rudloff took a small boat onto Öskjuvatn while Spethmann continued his research on the surrounding mountains. When Spethmann returned to camp in the evening, his companions were not there. He searched for five days before help arrived, but no trace of either man was found.

Knebel's fiancée, Ina von Grumbkow, traveled to Askja the following year to lead a second search. She and her team built a monument near the lake that still stands today and that doubles as a guestbook for visitors. A second monument, designed by the Austrian geologist Otto Woitsch, was eventually placed at the western part of the lake.

In 2014, observations after a major landslide at Askja led researchers to a new theory: a slope failure into Öskjuvatn during the 1907 visit could have generated a wave estimated at around 30 m (98 ft) high, large enough to capsize a small rowing boat. The theory is consistent with the lake's geometry and the steep walls surrounding it, but no physical evidence has been found and the case officially remains unsolved.

The story is the practical reason for the standing safety advice at Askja: do not enter Öskjuvatn, even on a calm day. Landslide-generated waves on small mountain lakes are sudden and very large, and there is no rescue infrastructure at the caldera.

NASA used Askja as a lunar-analog training ground for Apollo astronauts in 1965 and 1967, because the volcanic-desert terrain closely resembles the surface of the Moon.

Askja's position in the shadow of Vatnajökull, combined with its elevation, leaves the surrounding landscape almost entirely without vegetation. The area receives only about 450 mm (18 inches) of annual rainfall, which keeps it dry and exposed compared to most of Iceland. Volcanic deserts, fresh lava fields, and craters of varying ages give the area a surface texture geologists at the time judged closer to the Moon than almost anywhere else on Earth.

Two separate Apollo Geology Field research groups visited Iceland: the first in 1965, the second in 1967. The 1967 group focused specifically on Drekagil, Lake Mývatn, and Askja itself. During the training visits, astronauts including Neil Armstrong, Harrison Schmitt, Eugene Cernan, Bill Anders, and Edgar Mitchell practiced fieldwork they would later use on the lunar surface: identifying rock types, navigating featureless terrain, and collecting samples efficiently. The Exploration Museum in Húsavík covers this Iceland-Apollo connection in detail.

Askja is not accessible in winter for most travelers. The Icelandic Highlands are covered in snow and ice for most of the season, and the F-roads that lead to Askja are officially closed. The Highland F-roads close from October through late June, and only specialized super-jeep tours with experienced operators can reach the caldera during that time.

Independent winter visits are not advised: standard 4x4 vehicles cannot handle the conditions, route-finding becomes difficult or impossible without local knowledge, and rescue is far away. 

For travelers who specifically want a winter Highland experience, a small number of specialist operators run private super-jeep tours to Askja with modified vehicles and experienced guides. For everyone else, Askja is a summer destination.

Accommodation near Askja is extremely limited because of the remote location. Most travelers either base from Lake Mývatn for guided day tours, or stay at Highland huts when self-driving.

Highland huts: Dreki Mountain Hut, run by Ferðafélag Akureyrar (the Akureyri Touring Club) and set at the entrance to Drekagil canyon, is the closest accommodation to Askja and the natural choice for self-drivers wanting more time at the caldera. Booking ahead is essential. Laugarfell, further west on the Highland route, is another option for travelers planning a longer interior crossing.

Lake Mývatn area: For most travelers, Mývatn is the most convenient place to stay. Day tours to Askja depart from Reykjahlíð village, and the area has a full range of hotels and guesthouses. Mývatn is about 100 km (62 miles) northwest of the caldera.

East Iceland: The Wilderness Center near Egilsstaðir suits travelers approaching Askja from the east, combining the caldera with the eastern fjords on a longer trip. Other option in the wider east is Möðrudalur farm.

Camping: Camping near Askja is limited to a handful of practical options. Möðrudalur farm, about 70 km (43 miles) east of the caldera on Route 1, is a useful stop for travelers crossing the Highlands. Dreki Mountain Hut also has a small campground next to it during the summer access window. Pack everything you need, follow all park guidelines, and plan to be fully self-sufficient.

Askja is positioned in one of the most remote parts of Iceland, but a small cluster of Highland landmarks can be combined with the caldera on the same drive.

Lake Mývatn: the volcanic and geothermal region of North Iceland and the most practical starting point for a trip to Askja, about 100 km (62 miles) northwest, with Dimmuborgir lava field, Hverfjall crater, and the Námaskarð geothermal field.

Holuhraun lava field: an 85 km² (33 sq mi) basalt lava field about 15 km (9.3 mi) south of Askja, formed during the 2014 to 2015 Bárðarbunga fissure eruption and one of Iceland's most recent large lava flows.

Herðubreið mountain: a 1,682 m (5,518 ft) tuya often called the queen of Icelandic mountains, visible across much of the Askja approach and one of the most distinctive landmarks in the central Highlands.

Drekagil canyon: a steep, narrow canyon known for its volcanic walls, immediately next to the Dreki Mountain Hut and a short walk from the F894 turnoff to the Askja parking area.

Hrossaborg crater: a tuff-ring volcanic crater along Route 1 about 90 km (56 miles) northwest of Askja, used as a filming location for the 2013 science-fiction film Oblivion.

Námaskarð geothermal area: a high-temperature geothermal pass with steaming vents, mineral-stained ground, and bubbling mud pots near Lake Mývatn, about 105 km (65 miles) northwest of Askja.

Goðafoss waterfall: a 12 m (39 ft) horseshoe waterfall on the Skjálfandafljót river, about 145 km (90 miles) northwest of Askja, on the typical drive between Akureyri and Mývatn.

Dettifoss waterfall: one of the most powerful waterfalls in Europe by water volume, about 130 km (81 miles) north of Askja in the northern part of Vatnajökull National Park.

Askja is one of Iceland's most remote destinations. Plan carefully, check conditions before setting out, and be prepared for full self-sufficiency.

• Summer-only access. The F-roads to Askja are typically open from late June to early September. Outside this window, the caldera is effectively closed to all but specialist winter operators.
• Check conditions before you go. Always check road, weather, and Highland conditions at road.is and safetravel.is on the day of travel. Conditions can change quickly and the F-roads are not lit, signed, or maintained as paved roads are.
• 4x4 with adequate clearance is required. Standard 2WD cars are not allowed on F-roads, and small or low-clearance 4x4s struggle on the F88 river crossings. If unsure about your vehicle, take Route F905/F910 or join a guided tour.
• Pack everything you need. There are no fuel stations, shops, or reliable cell coverage in the Highlands. Bring layers, food, water, a full tank of fuel, and a basic vehicle kit.
• Register your route at safetravel.is. File a travel plan before setting out. This is the standard practice for Highland travel in Iceland and the easiest single thing you can do for safety.
• Take care at Víti. The path down to the crater is steep and loose, especially in wet weather. Wear sturdy shoes, take it slowly, and never enter the water if you are unsure of conditions.
• Do not enter Öskjuvatn. The lake has a documented history of sudden landslide-generated waves, including the one suspected of killing two scientists in 1907. Stay on the rim trails and the marked paths.
• Leave no trace. The caldera environment is fragile and recovers slowly. Carry out everything you bring in, stay on marked paths, and follow Vatnajökull National Park guidelines.