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Raufarhólshellir Lava Tunnel | A 5,000-year-old natural wonder near Reykjavík

ReykjavikLava Experiences IcelandRaufarholshellir Lava Tunnel

Why is Raufarhólshellir Lava Tunnel a must-visit attraction?

Just 30 minutes from Reykjavík, Raufarhólshellir Lava Tunnel is a real lava tube formed over 5,000 years ago. You’ll be walking the exact path molten lava once carved beneath the earth’s surface. 

It’s super accessible and transfers are included along with helmets and flashlights provided on the guided walk. Inside, you’ll see twisted lava walls, mineral-stained ceilings, and sections where daylight still filters in through collapsed skylights, creating dramatic contrasts. The temperature inside stays cool year-round, making it a comfortable option even in summer, and a memorable one in colder months. If you want an outdoor volcanic experience without committing to a long hike or technical terrain, Raufarhólshellir strikes the balance perfectly. 

Brief history of Raufarhólshellir Lava Tunnel 

~5,200 years ago

A massive volcanic eruption occurred in the Bláfjöll volcanic area, just east of present-day Reykjavík. As molten lava flowed across the landscape, the surface cooled while lava continued moving beneath it, forming what is now Raufarhólshellir, one of Iceland’s longest lava tubes.

Immediately after the eruption

Once the eruption ended, the lava drained out of the tunnel, leaving behind a hollow tube with layered walls, flow ridges, lava drips, and mineral deposits that clearly record how the lava once moved.

Centuries following the eruption

Natural weathering, groundwater seepage, and seasonal freezing shaped the tunnel further. In winter, ice formations began forming inside, adding a second, temporary layer to the ancient lava landscape.

Modern era (20th century)

Raufarhólshellir was recognized as a significant geological site due to its size, accessibility, and well-preserved volcanic features. It became an important reference point for understanding lava tube formation in Iceland.

Interesting facts about the Raufarhólshellir Lava Tunnel

  • It’s one of the longest lava tunnels in Iceland: Stretching over 1,300 meters, Raufarhólshellir is among the country’s most extensive lava tubes, long enough that you’re walking through multiple “chapters” of a single eruption.
  • The tunnel formed during a single eruption event: Everything you see, from the smooth walls to jagged ridges, was created during one continuous lava flow, not over centuries. The entire structure formed in a matter of days or weeks.
    Some ceiling drips froze mid-fall: Lava stalactites inside the tunnel formed when molten rock dripped from the ceiling and cooled almost instantly.
  • The floor preserves lava “traffic patterns”: Hardened ripples and channels show where lava sped up, slowed down, or split into different streams, allowing geologists to read the flow direction like frozen footprints.
  • It stays naturally cool year-round: The tunnel’s temperature remains close to freezing even in summer.
  • You’ll be walking through what was once an underground river of lava: At its peak, molten lava flowed through this tunnel like a pressurized river beneath the surface, carving the hollow space you walk through today.

Best time to visit Raufarhólshellir Lava Tunnel

The best time to visit Raufarhólshellir Lava Tunnel largely depends on what aspect of Iceland’s volcanic landscape you want to experience. From late spring through early autumn (May to September), conditions are milder and access from Reykjavík is straightforward, with clearer roads and longer daylight hours. This period highlights the tunnel’s geological textures like lava ridges, mineral-stained walls, and frozen flow patterns without seasonal ice covering it. Historically, this is also when Icelanders have traveled most easily across volcanic terrain, making it the most practical and predictable time to explore lava formations up close.

Winter visits (October to March) offer a very different perspective shaped by Iceland’s climate. As temperatures drop, water seeping into the tunnel freezes into striking ice crystals and columns. These formations are temporary and change each season, making winter tours uniquely time-specific. While access may be weather-dependent due to snow or icy roads, guided tours adapt accordingly, and the tunnel’s sheltered interior remains accessible. 

Frequently asked questions about Raufarhólshellir Lava Tunnel

Does the lava tunnel look different in summer and winter?

Yes. In summer, the focus is on exposed lava textures, mineral colors, and flow patterns. In winter, seasonal ice formations appear inside the tunnel, adding a temporary layer that changes every year.

How stable is a lava tunnel that’s over 5,000 years old?

Lava tubes like Raufarhólshellir are structurally stable because they’re made of solidified basalt. The tunnel has stood through thousands of years of seismic activity and is carefully monitored today for visitor safety.

Will I see running water inside the tunnel?

At certain times of year, especially during snowmelt or heavy rain, you may notice water seeping or dripping from the ceiling. This is part of the natural process that also creates winter ice formations.

How cold does it get inside the lava tunnel?

The temperature inside stays cool year-round, usually hovering just above freezing. Even in summer, it feels chilly, which helps preserve the tunnel’s features but means warm layers are essential.

Is lighting natural or artificial inside the tunnel?

The tunnel is naturally dark. Guided tours use installed lighting to highlight geological features, allowing you to see details without altering the environment.

Why is Raufarhólshellir considered one of Iceland’s most accessible lava tunnels?

Its wide passages, relatively short walking distance, and proximity to Reykjavík make it easier to explore than many lava tubes that require technical caving or long hikes.