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Þríhnúkagígur Volcano: Going Inside the Sleeping Giant of Iceland

Þríhnúkagígur (or Thríhnúkagígur as it’s primarily known in the English vernacular) is a two-for-one kind of deal. And in the Land of Fire and Ice, where volcanoes are a dime a dozen, this one is pretty unique.

So, if you have an upcoming trip to the island or just want to learn more about this fiery natural wonder of ours, read on. You might be surprised to find out what global importance it really holds.


What Makes Þríhnúkagígur So Special? 

Þríhnúkagígur is one of the volcanoes in Iceland, but it is considered dormant, with its last eruption having been over 4500 years ago. This volcano is so special and unique because it’s the only volcano in the world where you can access and explore its lava chamber (in layman’s terms, the cave where all the lava in a volcano is “kept”). So, visiting Þríhnúkagígur, as it sits in the beautiful Icelandic landscapes, will allow you to tick off another volcano visit here on the island. 

BUT if you take the elevator down the 212 meters (enough space for the Statue of Liberty to fit!) into the earth, an entire new world will open before you. There are all sorts of interesting rock formations and discolorations due to years of geological changes and volcanic events. And don’t expect a little cavern when we say cave; you can trek 3.5 kilometers inside Þríhnúkagígur. 

How Was Þríhnúkagígur Formed?

Þríhnúkagígur is actually the youngest and most northeastern peak of Þrihnukar, three peaks that formed after three volcanic eruptions. Þríhnúkagígur is a bit of a geological phenomenon in the sense that most volcanoes have lava that solidifies inside it after an eruption, but for some reason, Þríhnúkagígur has none. The theory is that the lava must’ve retreated back to the core of the earth, but for the most part, it’s still a mystery.


Either way, it makes Þríhnúkagígur incredibly important on a historical and geological front, since humans can now explore the inside of a volcano and be privy to millennia worth of data in the form of the layers of rock. For example, the cave floor dates back 30 to 40,000 years ago, roughly when modern humans first started walking the earth. 

inside volcano iceland

The History of Þríhnúkagígur

The discovery of Þríhnúkagígur was quite the adventure. The Blafjöll Ski Resort opened in 1970, and Arni Stefansson, who has always been a big cave enthusiast, heard about a cave there. He threw in a rock and waited for the thud that only came after 4 seconds. This meant that the cave was at least 100 meters deep.

On Midsummer’s Eve of 1974, Arni and eight others went to the cave, where Arni was lowered into the cave with a 200-meter rope he borrowed. Today, Arni jokes about what a disappointment it was, since he expected something resembling an Indiana Jones scene with stalactites dangling precariously over bubbling rivers of lava. He didn’t realize he had made history.

When Arni’s brothers, Einar and Björn, returned from a mountaineering trip, the three of them returned to the cave and, along with their partners who were the best mountaineering team in Iceland, started exploring the cave. They had their first two expeditions in 1991, whereafter they published articles about everything they had since found and discovered.

This, of course, was all the invitation the rest of the world’s cave explorers and geologists needed, and they, too, started flocking to the site. The cave only opened to the public in 2012.

thríhnúkagígur volcano

Where is Þríhnúkagígur?

Þríhnúkagígur forms part of Iceland’s Blue Mountain Range in the region of Hafnarfjördur, just a 35-minute drive from the capital city of Reykjavík. This, of course, makes it a great option as a day trip, but our personal preference for exploring the island will always be to have a road trip and include highlights such as Þríhnúkagígur along the way. This is also pretty easy to do since Þríhnúkagígur is just a few kilometers off our popular road trip route, the Ring Road. 

How to Get to Þríhnúkagígur in Iceland

You can choose to drive to Þríhnúkagígur yourself or book a tour departing from one of the cities. If you decide to drive yourself, you simply get on Route 1 (aka, the Ring Road) from Reykjavík and drive towards Road 417, where you will turn right. After about 4 kilometers, you will reach the parking lot, where you must take a short walk to the cave. 

If you’ve booked a tour that didn’t depart from one of the cities or towns in Iceland, you’ll probably meet each other at this parking lot. If you plan on booking a day tour to the volcano, you’ll need to set aside between 4-6 hours for your outing, and please keep in mind that no children under eight are allowed. Some of the most popular tours to go inside this famous volcano in Iceland are:

camper rental Iceland

When is the Best Time to Visit Þríhnúkagígur?

That will depend entirely on the weather you prefer and what activities and attractions you plan to do and see in Iceland during your trip (many of these are seasonal). Technically, you can visit Þríhnúkagígur all year round, but most tours allowing you to go inside the cave only operate during the warmer months of May to mid-October

Other Things to Do Near Þríhnúkagígur

If you want to check out what other wonders the area surrounding Þríhnúkagígur has to offer, you can consider adding the following to your Iceland bucket list:

Þríhnúkagígur; A Ring Road Road Trip Highlight

As we already mentioned, Þríhnúkagígur is located conveniently close to our popular Ring Road route, and there is no better way to explore the island than by making a road trip out of it. Just rent a campervan in Reykjavik upon your arrival on the island. 

That way, you have sorted out your transport as well as your accommodation and simply added to the unique experience and adventure of visiting Iceland, including making life-long memories in the magma chamber of Þríhnúkagígur.



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