I was in the middle of a vast lava field that stretched far into the distance. And I was about to descend a wooden stairway edged by snow, into a vast subterranean world created by a troll many centuries ago. This was the entrance to the Vidgelmir Lava Cave, the largest lava tube in Iceland.
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What Is The Vidgelmir Lava Cave?
Vidgelmir is in the Hallmundarhraun lava field, a massive area of basalt lava created around 900 CE by a single eruption that carried on for four years. During this time lava flowed down the valley and beneath the ground like a river, the outside forming a crust as the hot lava came into contact with the cold surroundings. Tubes were formed as the lava flowed through the hillside.

There may still be undiscovered lava tubes in the area: the Vidgelmir cave was discovered by chance following a rockfall. This is one of the largest lava tubes in the world, and a visit to Vidgelmir is like entering a hidden realm of eerie tunnels and strange rock formations.
History And Legends
Of course, as this is Iceland, there is bound to be a troll involved somewhere in the story. Whatever the scientific explanation, everyone knows that the lava field, and the tunnels beneath it, were created by the troll Hallmundur, who gave the area his name. (Some of Hallmundur’s exploits were recorded in the ancient Grettir’s Saga).

There is little evidence of any continuing human activity at Vidgelmir since its formation. However the discovery of some cooked animal bones seems to prove that at least one Viking was here at some point. Perhaps they were frightened off by the trolls and demons who frequent the cave!
A Tour Of Vidgelmir Cave
Our tour of Vidgelmir Lava Cave began by putting on hard hats – with torches attached – and walking down several flights of steps before reaching the body of the cave. Our guide was Katie, an English geologist, and she explained the history of the cave, its discovery and preservation, and the different rock formations.
We passed through an exposed area of snow and ice, noting the ice formations that would gradually melt as the summer progressed. Then we came to The Squeeze, a low and narrow passage through the rock. For someone like myself, who dislikes confined spaces, this was the worst part of the tour, but fortunately it was a fairly short stretch!

Strange Rock Formations
The next cavern was called the “Painted Room” on account of the colours of the rock, mostly red and yellow due to the presence of iron and sulphur. Katie pointed out a formation known as “lava ropes”, where it looked as if lines had been carved onto the ceiling. Further on was the “Chocolate Wall”, where lava had been squeezed through the rock as it contracted. In some places it had formed small stalactites and stalagmites.

We came to the end chamber, the rest of the cave being blocked off for preservation and safety purposes. Here we switched off our head torches, and Katie turned off the light. We stood for a moment in pitch darkness, with no sound but the dripping of the water in the cave.

We walked back through the cave the same way as we had come, then re-emerged into the light and (comparative) warmth of the lava field.
How To Visit The Vidgelmir Lava Cave
- Vidgelmir is around a 2 hour drive from Reykjavik, with a section of unmade road at the end. (Note the Icelandic spelling Víðgelmir on road signs.)
- The cave is privately owned and the only way to explore is via a tour, which lasts 1½ hours. You can purchase tickets on arrival, or book in advance.
- It is cold in the cave and warm clothing is recommended. Strong shoes or boots are essential.
- Although there are walkways through the cave the ground may be slippery or uneven in places, and there are steps at the entrance. There is no wheelchair access and the tour may be unsuitable for anyone with mobility issues.
- It is also possible to visit Vidgelmir as part of an organised day trip from Reykjavik.






