Hallmundarhraun flowed from an eruption of one of the volcanoes lying under the Langjokull glacier around the year 930. Consisting of dark basaltic rocks covered in soft moss, there are wonderful formations, frozen ripples, crevasses, and Surtshellir cave located underneath. The ancient lava flow gets it name from a cave-dwelling giant from the Saga of Grettir the Strong.

Hallmundarhraun is a lavafield that formed shortly after Iceland’s settlement, in the 10th century. The lava field gets its name from Hallmundur which according to Gretti’s Saga lived in this area. The craters from which the lava flowed are located below Langjokull glaciers. The eruption lasted for several years. It is over 200 km² in area. The largest part of the lava is 7 km and its total length is 52 km.

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A remarkable narrative of this eruption is in an ancient song called Hallmundarkvida or Poem of Hallmundur. This is the oldest description of an eruption in Iceland. There are reports of earthquakes, ash, lava flow and deaths caused by the eruption. It is likely that the eruption has occurred around 940. There may be some farmsteads that went under the lava.

In Hallmundarhraun there are many caves, the most famous are Víðgelmir, Stefánshellir and Surtshellir.

Check out our complete guide to the Golden Circle and West Iceland