Raufarhólshellir

Raufarhólshellir is one of the longest and most walkable lava tubes in Iceland, a tunnel some 1,360 metres long that runs beneath the lava fields east of the Bláfjöll mountains. It was drained empty a little over five thousand years ago, during the Leitahraun eruption, when a river of molten rock kept flowing inside a crust that had already hardened around it. When the eruption stopped, the liquid core ran out and left the shell behind: a passage that is typically ten metres high and up to thirty metres wide, large enough in places to feel more like a hall than a cave.

What makes the tube memorable is how much of the sky gets in. Near the entrance the roof has collapsed in several places, and these skylights drop shafts of daylight onto heaps of fallen basalt; in winter snow drifts in through them and ice builds up into stalagmites and glassy sculptures on the floor. Deeper in, the walls carry the record of the flow itself: horizontal "bathtub rings" where the lava level paused, and a surprising palette of rust red, ochre and yellow on black rock, which the tunnel's lighting brings out. The road above, Route 39, actually passes over the tube where it is around fifteen metres across.

For years the cave was open to anyone, and visitors broke off nearly all of its delicate lava straws. Its otherworldly interior has also served as a film set, appearing in the film Noah (2014) and in the series Sense8.

Getting there

Raufarhólshellir lies about 33 km from Reykjavík, roughly half an hour by car, off Route 39. The closest airport is Reykjavík Domestic Airport (RKV), about 34 km away. Tours run all year, including options with transport from Reykjavík; a helmet and lamp are provided.