Top 10 Caves in Iceland
Iceland sits on the Mid-Atlantic Ridge and over a mantle hotspot, producing a landscape of active and recently active volcanism. Its caves are overwhelmingly volcanic rather than karst in origin — lava tubes formed during historical and prehistoric eruptions, some of which have accumulated ice to create hybrid environments. The glacier ice caves of Vatnajokull are a separate category entirely: glacial passages in basaltic rock beneath the ice cap, seasonally accessible and constantly changing. No other country offers as concentrated a range of different cave types within a small area.
All caves here are on the cave map.
1. Vatnajokull Crystal Ice Cave, Southeast Iceland
Glacial ice cave. The crystal ice caves accessed via Jokulsarlon glacial lagoon are Iceland's most photographed underground environment. The vivid blue colour of the compressed glacial ice — caused by ice density absorbing long-wavelength visible light — and the contrast with black basalt walls make these chambers visually extraordinary. Different cave sections form each winter as meltwater drainage patterns shift; tours are guided, group-limited, and operate only between October and March. Access via Jokulsarlon, approximately 370 kilometres from Reykjavik. Tour grade B.
2. Langjokull Glacier Tunnel, Western Iceland
Man-made ice tunnel. The Langjokull tunnel network on Iceland's second-largest glacier is not a natural cave but a purpose-excavated tunnel system extending 500 metres into the ice from an entrance near the glacier surface. The tunnels pass through ice layers that carry annual accumulation strata, allowing visitors to see decades of compressed snowfall. Accessed by specially equipped glacier vehicle from the Husafell area. Open year-round; the ice walls remain stable because the tunnel is entirely within the glacier body rather than in the ablation zone. Tour grade A.
3. Raufarhólshellir Lava Tube, Capital Region
Lava tube. The most accessible cave from Reykjavik, Raufarhólshellir is located approximately 30 kilometres east on the Reykjanes Peninsula. The tube formed during the Krísuvík eruptions approximately 5,200 years ago and extends about 1,360 metres. A commercial operation runs daily tours with installed lighting through the first 900 metres; winter tours include ice formations in the entrance section. The cave ceiling reaches 10 metres in the largest sections. Tour grade A to B.
4. Víðgelmir Lava Tube, Borgarfjördur
Lava tube. Víðgelmir near Husafell in Borgarfjördur is Iceland's largest lava cave by volume, with a main passage approximately 1,585 metres long and ceiling heights reaching 16 metres. The cave formed during an eruption of the Langjokull volcanic system approximately 900 years ago, placing its formation within the historical period of Icelandic settlement. The entrance section contains ice formations; the deeper tube sections are ice-free. Guided tours from a purpose-built visitor centre. Tour grade B.
5. Lofthellir, Lake Myvatn Area
Lava tube with ice. Lofthellir near Lake Myvatn in northeast Iceland is a lava tube cave notable for an interior chamber where ice has accumulated over centuries to form an extraordinary display of ice stalagmites, columns, and a frozen floor — static ice formations in a volcanic rock cave rather than glacial ice. The cold-air-trap mechanism of the cave's geometry preserves the ice year-round. Access requires a guided 4WD transfer and a 30-minute walk across lava fields. The cave is small and the tour group is deliberately limited; advance booking is essential. Tour grade B.
6. Þríhnúkagígur (Inside the Volcano), Reykjanes
Volcanic chamber. Þríhnúkagígur is unique in the world: a dormant shield volcano whose magma chamber has been emptied by drainage, leaving a vast open chamber accessible by lift from the summit crater. The chamber is approximately 120 metres deep and wide enough at its base to contain the interior of a large cathedral — considerably larger than most karst cave chambers open to visitors. The basaltic walls are stained in vivid mineral colours — reds, ochres, purples, and greens — from the hydrothermal alteration of the original eruption. Open May to October only. Tour grade A (with a lift descent).
7. Surtshellir Lava Tube, Borgarfjördur
Lava tube. Surtshellir is one of Iceland's longest lava tubes at approximately 3.5 kilometres, formed during the eruption of the Hallmundarhraun lava field around 1,100 years ago. It was used as a bandit hideout in the Viking age — the Icelandic sagas record the outlaw Svipur sheltering in the cave. Bones and artefacts from the saga period were recovered in archaeological surveys. The cave is publicly accessible without a guide; helmets and headlamps are required. Tour grade B.
8. Grjótagjá, Lake Myvatn Area
Geothermal hot spring cave. Grjótagjá is a small lava cave near Lake Myvatn that contains a geothermal pool of clear blue water heated to 43-46°C, entering through fissures in the cave floor. Bathing was prohibited in 2010 following increased geothermal activity that raised temperatures to unswimmable levels (though they have since stabilised). The cave became internationally known after being used as a filming location in Game of Thrones. Visitors can enter and view the pool; the cave is owned by local farmer Jon Stefansson. Tour grade A.
9. Stefánshellir, Borgarfjördur
Lava tube. Stefánshellir is geologically connected to Surtshellir in the Hallmundarhraun lava field and together the two tubes form one of the longest lava tube systems in Iceland. The passage is narrower and lower than Surtshellir, providing a more technical cave experience. Several significant ice formations are present in the colder sections. Self-guided access; good lights and warm clothing required. Tour grade B.
10. Buri Cave, Snæfellsnes Peninsula
Lava tube. Buri is a lava tube cave on the Snæfellsnes Peninsula, in the shadow of the Snæfellsjokull glacier that Jules Verne used as the fictional entry point to the centre of the earth in his 1864 novel Journey to the Centre of the Earth. The cave formed during the volcanic activity that built the Snæfellsnes Peninsula and contains sections of lava stalactites (lavacicles) and smooth tube walls. Guided tours are available from operators based in Arnarstapi and Hellnar. Tour grade A to B.
Planning an Iceland cave trip
Iceland's cave geography divides naturally into three clusters. The Reykjavik region offers Raufarhólshellir and Þríhnúkagígur (Inside the Volcano), both accessible on day trips from the capital. The Borgarfjördur and Snæfellsnes area — three to four hours northwest of Reykjavik — contains Víðgelmir, Surtshellir, Stefánshellir, and Buri. The Myvatn area in the northeast includes Lofthellir and Grjótagjá, combining well with the Myvatn geothermal landscape and Dettifoss waterfall. The Vatnajokull and Skaftafell ice caves require a southeast Iceland base and a winter visit (October to March).
Most lava tube caves require helmets and good headlamps; the cave temperature in Iceland's lava tubes ranges from around 2°C to 6°C year-round. Layering for cold is essential regardless of the surface temperature. Raufarhólshellir and Víðgelmir both supply helmets and headlamps for visitors on guided tours, making them accessible with no personal equipment. For the ice caves of Vatnajokull and Skaftafell, all gear — crampons, safety ropes, helmets — is supplied by the tour operator; visitors need only waterproof outer layers and warm mid-layers. Iceland's cave tourism sector is professional and well-regulated; all guided tours operating within Vatnajokull National Park require park-issued permits. The Icelandic Speleological Society (Hellir) manages the national cave register and coordinates access to caves outside the national park system. For wild lava tube exploration beyond the toured sections of Raufarhólshellir, Víðgelmir, and Surtshellir, contact with Hellir or local outdoor clubs is the appropriate starting point. The cave flora of Iceland's lava tubes — mosses, liverworts, and the cold-adapted invertebrate communities that feed on them — is a distinct ecological zone separate from both the cave interior and the surrounding lava field surface.