Askja: A Deep Dive into the Caldera Where Astronauts Trained
Deep in the remote highlands of Iceland lies Askja, a complex of calderas set in one of the most desolate and otherworldly landscapes in the country. Its 1875 eruption spread ash that ruined farmland and helped drive a wave of emigration from Iceland to North America. A century later, its barren, lunar terrain was chosen as a training ground for the Apollo astronauts preparing to walk on the Moon.
A caldera in the highlands
Askja is a central volcano with a set of nested calderas, lying in the remote interior highlands of Iceland within the Vatnajokull region. Reaching around 1,500 metres, it sits amid a vast, barren landscape of lava, ash, and sand, far from any settlement. Its isolation and starkness make it one of the most striking and remote volcanic sites in Iceland.
The 1875 eruption
In 1875, Askja produced a major explosive eruption that spread ash across the eastern part of Iceland. The ashfall devastated farmland and grazing, contributing to severe hardship in an already difficult time. The eruption is widely linked to a wave of emigration from Iceland to North America, as families left a homeland made harsher by volcanic disaster.
The Viti crater lake
One of Askja's most distinctive features is Viti, a crater formed during the 1875 eruption that now holds a warm, milky-blue geothermal lake. Set within the larger caldera, Viti contrasts with the cold, clear waters of the adjacent Oskjuvatn, the deep lake that fills much of the main caldera. The warm waters of Viti draw adventurous visitors who make the long journey to bathe in this remote crater.
Training the Apollo astronauts
Askja's barren, rocky terrain, resembling the surface of the Moon, led to its selection as a training site for the Apollo astronauts in the 1960s. Crews who would later walk on the Moon practised geological fieldwork among Askja's lava and ash, learning to recognise and sample volcanic rocks in a landscape that mimicked their lunar destination. This remarkable chapter links the remote Icelandic highlands to the history of space exploration.
A landscape of lava and sand
The Askja region is part of a vast volcanic desert, where eruptions over thousands of years have built a landscape of lava fields, ash plains, and dark volcanic sand. The area is shaped by both volcanism and the harsh highland climate, creating an environment of stark, austere beauty that feels truly otherworldly.
A remote destination
Reaching Askja is an adventure in itself, requiring travel across rough highland tracks that are only passable for part of the year. The remoteness, combined with the dramatic caldera, the Viti crater lake, and the lunar landscape, makes Askja a sought-after destination for travellers seeking the wild heart of Iceland's interior.
An active system
Although it has been relatively quiet in recent decades, Askja remains an active volcanic system, and signs of unrest such as ground deformation have prompted heightened monitoring at times. Iceland's geological agencies watch Askja for any indication of renewed activity, mindful of the power demonstrated by its 1875 eruption.
Explore on the map
Askja stands among Iceland's great volcanic systems, alongside Bardarbunga, Grimsvotn, and Hekla. Explore it on the interactive map — filter by country to see Askja among Iceland's volcanoes and to appreciate the remote, otherworldly volcanism of the island's highland interior.