Raufarhólshellir lava cave can be found close to road (nr.39) on the northern side of the top of a hill that slopes on the southern side towards the sea and the town of Þorlákshöfn. The cave is not clearly visible from the road, but the entrance is east of the road.
A section of the approximately 1360 m long cave lies under the road in northwest direction. It is 10-30 m wide and up to 10 m tall, and the roof is generally about 12 m thick, except under the road where it is thinner.
Raufarhólshellir is the fourth longest cave in Iceland and the longest outside of the Hallmundarhraun lava field in the Borgarfjörður region. The cave formed as a lava tube during the Leitahraun eruption, which occurred east of the Bláfjöll mountains about 4600 years ago.
The cave’s entrance is only 20-30 m east of the road. Several small openings down to the cave can be seen in the first 100 meters but the one nearest to the road is main entrance.
Sigurður G. Kristinsson, 2010