Raufarholshellir Lava Cave

The tube is up to 30 metres wide and at least 10 metres high along most of its length. Daylight drops in through holes in the ceiling, and snow piles up on the floor underneath them. The walls carry red and ochre bands where the lava last ran, 5,600 years ago. Ice formations and lava stalactites build up inside. Groups walk in on decking, then over broken lava rock, and at one point the guide switches the lights off and the darkness is total. The standard tour covers only the section nearest the entrance; the deeper part of the tube is a separate, longer tour.

• Guided tours only. You cannot go in alone. The standard tour covers the first part of the tube; going deeper is a separate tour.
• The floor is broken lava. Helmets with head torches and walking sticks are handed out at the start. Wear sturdy shoes.
• Not step-free. The entrance is not wheelchair accessible, and the route inside includes stairs and rough rock.
• Book before you drive out. Tours run in timed slots with a limited number of places, and walk-in space is not guaranteed.
• Facilities. There are toilets on site, and the tour takes children.

Route 39 crosses over the cave, at a point where the tube is about 15 metres across. There is a free car park on site, and everything from there is on foot and with a guide. The walk in starts on decking and lighting installed in the section nearest the opening, then continues over stairs and loose lava rock. Helmets with head torches and walking sticks are issued before you go down.

Better: wet and windy days. The cave is roofed and lit, so the weather above ground changes nothing about the visit.

Avoid: turning up without a booking. Entry is by timed slot with a limited number of people on each tour.

Inside, the light is artificial apart from the daylight falling through the holes in the ceiling, so no hour of the day is better than another for photographs.