Comparison
Iceland has two completely different kinds of cave, made by the two forces the country is named for. One is seasonal and made of ice. The other is 5,000 years old, made of stone, and open every day of the year.
An ice cave is a void inside a moving glacier, carved by meltwater, and mostly seasonal. A lava tube is a hollow left in solid rock by a drained lava flow thousands of years ago, and open all year.
| Ice cave | Lava tube | |
|---|---|---|
| Made of | Glacier ice | Solid basalt |
| Formed by | Meltwater erosion, annually | Draining lava, thousands of years ago |
| Age | Months | Thousands of years |
| Season | Mostly winter | Year-round |
| Changes? | Completely, every year | Essentially never |
| Nearest to Reykjavik | ~2 hrs | ~30 min |
| Inside temperature | Around freezing | Steady, a few degrees above freezing |
| Cancels for weather? | Regularly | Rarely |
A river of lava crusts over on the outside while still flowing inside. When the eruption stops, the molten core drains away and leaves a hollow tube.
It is the same principle as ice on a river, at about a thousand degrees. The surface of a lava flow cools against the air and hardens into a roof, insulating the lava beneath, which keeps running. When the supply is cut off, the remaining lava drains downhill and the tunnel is left behind.
Raufarhólshellir, the best-known example near Reykjavik, was formed in the Leitahraun eruption roughly 5,200 years ago. It is Iceland's fourth-longest lava tube at about 1,360 metres, reaching up to 10 metres high and 30 metres wide in places, with skylights where sections of roof have collapsed.
Different, not ranked. Ice caves win on colour and rarity; lava tubes win on scale, permanence and reliability.
Whenever the ice caves are shut, when you are short on time, or when the weather has closed the South Coast.
| Situation | Better choice |
|---|---|
| Visiting May to September | Lava tube, or the year-round ice caves |
| Only have a half-day from Reykjavik | Lava tube — about 30 minutes away |
| Storm has closed the South Coast | Lava tube — rarely affected |
| Want the blue ice from the photographs | Ice cave, in winter |
| Travelling with limited mobility | Lava tube — some have walkways, though none is fully accessible |
| Want both ice and rock | Lava tube in midwinter, for the ice formations |
| Cave | Where | Notes |
|---|---|---|
| Raufarhólshellir | ~30 km from Reykjavik | The most accessible. Walkways and lighting installed; standard tours around an hour |
| Víðgelmir | West Iceland | Known for well-preserved lava stalactites and flow formations |
| Vatnshellir | Snæfellsnes peninsula | Around 8,000 years old, entered vertically by spiral staircase; tours about 50 minutes |
| Lofthellir | Mývatn, north Iceland | Contains substantial natural ice formations; involves crawling and is much more demanding |
Raufarhólshellir is the one most visitors see, largely because of its proximity to the capital and the Golden Circle. It was closed in late 2016 so that accumulated rubbish could be cleared and a walkway and lighting installed, and reopened for guided tours the following year.
Cool, dark, echoing and steady. Lava tube interiors hold a fairly constant temperature a few degrees above freezing regardless of the weather outside.
That means it can feel warmer than an ice cave in midwinter and considerably cooler than the air outside in July. Either way you want warm layers, and sturdy shoes with grip: the floor is rocky and uneven even where walkways have been built.
Helmets are provided and worn for a reason — ceilings vary in height and rock does come down. As with ice caves, entry is on guided tours rather than unaccompanied.
Comfortably. They are in different places and different price brackets, and a lava tube fits into a half-day that an ice cave never could.
A common and sensible pattern is a lava tube on an arrival or departure day near Reykjavik, and an ice cave as the centrepiece of a South Coast leg. Because the tube is around thirty minutes from the city and tours run roughly hourly, it slots into gaps that nothing else fills.
If your dates fall outside the natural ice cave season, the strongest pairing is a lava tube plus the year-round Langjökull ice tunnel — one made by fire, one cut into ice, both open in July.
If you can only do one and you are travelling in winter, do the ice cave. If you are travelling in summer, or your plans are fragile, do the lava tube.
Ice caves are genuinely rarer. There are lava tubes in Hawaii, the Canaries, Sicily and Korea; there are very few places on earth where you can walk into a blue chamber inside a glacier, and fewer every decade. But a cave you cannot reach because the road is shut is worth nothing, and a lava tube on a stormy Tuesday is worth a great deal.
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