The Only Volcano on Earth You Can Explore From the Inside

Lava plains

Over the years, we’ve all seen some pretty amazing photographs of volcanoes – from epic eruption shots with rivers of bubbling lava, to more peaceful images of dormant volcanoes and water-filled craters. In fact, the only perspective we don’t see very often is what a volcano looks like from the inside. Obviously, few people would be crazy enough to explore the interior of an active volcano, and even dormant volcanoes are normally inaccessible as they tend to be plugged up with solidified lava. Thrihnukagigur volcano in Iceland is the only known exception.

It’s a long way down…

Iceland is well known for its volcanic landscape. And in April 2010, eruptions in Eyjafjallajökull made international news when the expelled clouds of ash caused almost a week of disruptions to air traffic all over Northern and Western Europe.

Beginning the descent into Thrihnukagigur

In all, there are 30 active volcano systems in Iceland, with this large number a result of the country’s position on the volatile mid-Atlantic ridge. So for anyone interested in studying volcanic systems, Iceland is the place to go!


Colorful rocks on the way down

Even in a country full of volcanoes, Thrihnukagigur (which translates as “three peaks crater”) is unique. It’s also a valuable resource for scientists, offering the kind of geological study that can’t be carried out anywhere else on Earth. But of course, scientists aren’t the only people fascinated by volcanoes, and Thrihnukagigur is an interesting place to explore for anyone – except perhaps the claustrophobic.


Reaching the bottom

Thrihnukagigur has lain dormant for the past 4,000 years – since long before humans arrived on Iceland. It was first discovered in 1974 and was fully explored and mapped out in 1991. Entry into the magma chamber is via a 13×13-foot (4×4-meter) opening. The chamber then drops down 394 feet (120 meters) below the surface. The crater itself is bottle shaped and its cave a whopping 5,300,000 cubic feet (150,000 cubic meters) in size.

Descending into the magma chamber

The first person to descend into the volcano was cave explorer Arni Stefánsson. Amazingly, he describes his first visit as disappointing. “I came looking for beauty, but I found ugliness,” he says. And it was enough to keep him away for 17 years. However, when he finally did make a second trip, Stefánsson found the experience completely different. Perhaps it was because he took better lights and spent more time exploring the volcano second time around.


More impressive colors on the walls of the chamber

Visitors must begin their journey in the Blue Mountains region, not far from Reykjavik. From there, they have to hike to Thrihnukagigur, which is a 45-minute trip that takes them past volcanic fields, gas tunnels and sculpted volcanic cones. Explorers are then lowered into the volcano by a special lift. Compare Stefánsson’s first trip, which involved him descending into the volcano by rope in darkness! As you can see in these photographs, the textures and colors of the lava on the walls are quite spectacular.

Textures of lava

Nobody knows exactly how the magma chamber in Thrihnukagigur was emptied. It’s possible that the lava stuck to the walls and solidified, or it may have just sunk back down into the Earth. Volcanologist Haraldur Sigurdsson says, “It’s like somebody came and pulled the plug and all the magma ran down out of it.”


Lava has left a streaky pattern on this wall.

Magma originates from cracks in the Earth’s crust, and when its way to the surface is blocked, it gathers in magma chambers. As more and more magma continues to pour into such chambers, the pressure increases. This pressure is what can eventually lead to a volcanic eruption, as the magma forces its way to the surface.

This area was once filled with bubbling molten rock.

Even though it has been dormant for thousands of years, walking around a volcano can still be a little unsettling. What’s more, it becomes even more nerve-wracking when you realize that just because the volcano hasn’t erupted for a long time, this doesn’t necessarily mean it will never erupt again. Still not scared? Well, there’s also the danger of an earthquake, which could leave explorers crushed or buried under falling rocks.


Incredible beauty born out of extreme volcanic violence

Still, for some people, the wonderful scenery inside the chamber makes it worth the risk. The kaleidoscope of colors on the cave walls is the result of minerals within the volcanic rock. Red indicates higher amounts of iron; more silica leads to lighter colors; and basalt is dark, as it contains hardly any silica but a lot of iron and magnesium. Those without any interest in geology can simply marvel at the beautiful patterns and colors.

Explorers can’t resist taking photographs in such a unique location.

All lava caves in Iceland are under government protection. Nevertheless, tourists are encouraged in the interest of education. Work is being done to preserve Thrihnukagigur and make it more accessible to the public. On top of the tours currently on offer, there are plans to construct a tunnel leading to the chamber, which would make visiting the volcano even easier.


Moss grows on the rocks, adding yet another hue to the volcano’s colorful palette.

As mentioned earlier, besides being an intriguing place to visit, Thrihnukagigur and its unique magma chamber are also important resources for researchers. What they learn there will help them understand active volcanoes like Eyjafjallajokull, Katla and others. And with the constant threat of volcanic eruptions in Iceland, this kind of study is invaluable.

Back in the sunlight

On an island that already seems to have its fair share of natural wonders, Thrihnukagigur still manages to stand out. “Coming here is a chance to feel your own smallness, to tackle your own fears,” says Stefánsson. “I want people to come here and feel humble.” And since there’s an overwhelming demand for tours of the volcano, it looks like he will get his wish.

Sources: 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13