Raufarhólshellir Lava Tunnel

What a lava tunnel actually is

Lava tunnels form when the outer surface of a flowing lava stream cools and hardens while molten rock continues flowing beneath it; once the eruption ends and the remaining lava drains out, it leaves behind a hollow tube. Raufarhólshellir, formed roughly 5,000 years ago, is one of Iceland's longest at over a kilometre, with sections wide and tall enough to comfortably walk through standing upright — genuinely different from squeezing through a cramped cave, which surprises many first-time visitors.

What you'll see inside

The tunnel's walls and ceiling show mineral staining in deep reds, oranges and blacks, along with visible lava formations — ropey textures where the surface cooled mid-flow, and in some sections, delicate ice formations in winter where meltwater freezes as it drips through cracks from above. Skylights where sections of the tunnel roof have collapsed let natural light filter into parts of the cave, creating a striking contrast with the darker sections deeper in.

Guided tour or self-guided?

Raufarhólshellir is run as a managed site with both a shorter, easier standard walking tour suitable for most fitness levels along a fixed walkway, and a longer, more adventurous caving tour into less-developed sections requiring scrambling over uneven terrain and, at times, tighter spaces. Independent access isn't offered — a guide and proper equipment (helmets and headlamps, provided as part of the tour) are required, partly for safety and partly to protect the cave's delicate formations from damage.

Practical details

• Roughly 30–40 minutes from Reykjavik, making it one of the easiest cave experiences to fit into a shorter trip or a layover.
• Wear warm layers regardless of the weather outside — the cave interior stays cool year-round.
• Sturdy, closed-toe shoes are essential, especially for the longer caving tour option.
• Tours run through the year, unlike ice caves, which are strictly seasonal — a useful option if your trip falls outside ice cave season (roughly April–October).