Thrihnukagigur volcano

A journey into the magma


Thrihnukagigur volcano, Höfuðborgarsvæðið, Iceland

GPS: 63.998845691015, -21.698092244576

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Thrihnukagigur is a dormant volcano in southwest Iceland. It is the only place on Earth where it is possible to enter an authentically preserved magma chamber. This dormant volcano with an unpronounceable name is in the Bláfjöll mountain range (blue fells), about 20 kilometres southeast of Reykjavik. Its Icelandic name (Þríhnúkagígur) can be translated as “Three Peaks Crater”. Indeed, two other non-explorable craters adjoin the Thrihnukagigur volcano that last erupted about 4 000 years.

The Thrihnukagigur massif and the Bláfjöll mountains are part of a protected area adjacent to the Hellisheidi lava plateau (Hellisheiði). The volcano and its funnel-shaped opening were discovered in the 1970s by the cave explorer Árni B Stefánsson. Entering the heart of the volcano, Stefánsson was amazed by the profusion of colours of the basalt rock and the gigantic size of the magma chamber. Shades of bright and dark colours sprinkle the inner walls of the volcano like a canvas painted in the dark by Mother Nature. Stefánsson negotiated for several years with the Icelandic authorities to open the site to the public while ensuring its protection.

Since 2012, a certified tour operator (3H Travel) offers the unique opportunity to see what an extinct volcano looks like from the inside. Accompanied by experienced guides, you will discover an incredible natural phenomenon through a 120-metre descent into the depths of the Thrihnukagigur volcano. This day trip from Iceland’s capital is open to everyone. Admission is not limited to experienced cavers (the descent is made by a gondola). The hike on the Icelandic highlands to get to the site takes less than an hour (3 kilometres) and follows a slightly uneven terrain (100-metre difference in altitude). You will be served a cup of soup after your underground exploration to help you recover from this fantastic journey into the bowels of the Earth.

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  • A fabulous and rare geological heritage for you to experience first-hand
  • The surprising discovery of a magma chamber emptied of its lava in the Earth’s abyss
  • A memorable experience and a site that is unique in the world
  • The impressive size of the crater and its magma chamber
  • The technique of immersion by gondola in complete safety, like a spider hanging on a thread
  • The bottle-shaped vault (over 210 metres deep); the funnel-shaped opening (3.5 metres in diameter)
  • The striking alliance of the mineral colours of the basaltic rocks within the volcano (surprising mixture of yellow, orange, red, ochre, green, blue, black…)
  • Hiking on the old lava fields (including Kristnitokuhraun); the nearby Leidarendi lava tube; the lunar landscapes of the Bláfjöll mountain range (Iceland’s blue fells); downhill and cross-country skiing in winter
  • The panoramic view over several kilometres from the top of the volcano
  • Iceland is one of the most volcanic regions in the world. Iceland has some 130 active volcanoes of which about 20 have erupted since the arrival of the first settlers in the early 10th century.
  • According to a legend, the places similar to the Thrihnukagigur volcano (mountains, rocky environments, caves…) were inhabited by fantastic creatures called Huldufólk. These “hidden people” consisted of elves, trolls and invisible beings who created their cities (Álagablettur). They rose against anyone who attempted to steal or plunder Iceland’s natural wealth.
  • Exploring the Thrihnukagigur volcano is possible because of the absence of magma in the inner tube (equivalent to the loss of a cork on a wine bottle). Normally, after a volcano erupts, its crater is covered with cold, hard lava that has solidified, creating a solid plug. It can also happen that the top of the crater collapses on itself. But in this case, the lava of Thrihnukagigur volcano has disappeared by coagulating on the walls or by sinking into the Earth, leaving behind an impressive cave.
  • According to the guides, the main chamber of the Thrihnukagigur volcano is so large that it could hold three basketball courts on ground level, reaching up to the height of the Statue of Liberty.
  • The construction of a tunnel to reach the magma chamber is under consideration, as well as the impact of the project on this heritage site.
  • The conditions of access to the crater can vary. It is important to inquire and book in advance with 3H Travel through the tour called Inside The Volcano (the descent is not allowed to children under 12 years).
  • Visits are only allowed between May and September (it is forbidden to leave with a piece of rock from inside the Thrihnukagigur volcano).
  • Take along warm clothing, irrespective of the weather.
  • Not far from the volcano, you can explore two caves and the lava tunnel Leiðarendi. For safety reasons, this activity should be done in the presence of an experienced guide with all necessary equipment (helmet, lamp, gloves, boots and crampons in winter). Waterproof clothing is strongly recommended.

Where to eat

  • Norðurbakkinn
    (literary café)
  • Von Mathús & Bar
    (typical Icelandic dishes)
  • Tilveran
    (delicious lobster)

Where to go

  • Kleifarvatn
    (wild lake)
  • Geothermal springs of Seltún
    (series of steaming pools)
  • The Icelandic Horse
    (horseback riding)

Where to stay

  • Lava Hostel
    (camping site and hostel)
  • Edda´s Farmhouse In Town
    (mini urban farm)
  • Árós B&B
    (well maintained)