The Sundhnukagigar volcano system has had regular eruptions since 2023. In the years since, it’s put on a fiery show with lava fountains spraying over 150 feet high, most recently in April 2025. What can we say? That’s why they call this nation the land of fire and ice.
Sundhnukagigar isn’t just a single volcano. It’s a row of craters just outside the small fishing town of Grindavik, which sits on the Reykjanes Peninsula in Southwest Iceland. However, it's not the same as the volcano in Fagradalsfjall, which erupted in 2021 and 2022. Sundhnukagigar is part of the ongoing volcanic eruptions on the Reykjanes Peninsula.
The newest eruption of Sundhnukagigar Craters started on the morning of April 1st, 2025. It marked the 8th Sundhnukagigar eruption since late 2023, and the 11th eruption on the Reykjanes Peninsula since 2021.
Travelers seeking an up-close look at this mighty volcano must do so with a volcano helicopter tour. Accessing the volcanic area on foot is restricted due to the ongoing eruptions and safety concerns. However, these eruptions have not had any effect on travel in Iceland, and daily life goes on as normal for locals.
Authorities have closed the site to the public to ensure visitor safety. Newly formed lava fields are unstable and emit hazardous gases. It's crucial to respect these closures and avoid attempting to enter the area on foot until authorities deem it safe to do so.
Key Takeaways
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Earth's Crust in Action — The Sundhnukagigar eruptions are the dramatic result of Iceland's position on the Mid-Atlantic Ridge, creating a fiery display every few centuries.
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From Tourist Attraction to Hazard Zone — While earlier eruptions like Fagradalsfjall drew crowds, the Sundhnukagigar events became increasingly intense and dangerous, leading to evacuations, infrastructure damage, and a shift away from sightseeing to careful monitoring.
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Science Prevails — Iceland's sophisticated monitoring system of seismometers, GPS, and satellites allows scientists to predict eruptions and keep people safe, showcasing the power of technology in managing natural disasters.
Geological Background
Photo from Wikimedia, Creative Commons, by TommyBee. The area in 2022. The Capital Area and lava from the Fagradallsfjall eruptions are in the top right, and Grindavik to the bottom left. The old Sundhnukagigar craters are the dark crack in the middle of the peninsula, above the right edge of Grindavik.
The Sundhnukar Crater Row is part of the Reykjanes Peninsula’s volcanic system. This relatively young geological feature lies within the Svartsengi Volcanic System. This region is part of the larger Mid-Atlantic Ridge, where the Eurasian and North American tectonic plates are actively spreading apart, leading to frequent volcanic and seismic activity.
As the tectonic plates drift farther apart, they create “rift zones” that produce basaltic lava flows. Icelandic volcanoes produce a distinct type of highly fluid lava that can spread over large areas and form extensive lava fields.
The Reykjanes Peninsula experiences eruptive cycles approximately every 800–1,000 years. Before becoming active in 2021, the most recent eruption occurred over 800 years ago. This region is home to the Svartsengi Power Station, which heats the famous Blue Lagoon.
Sundhnukagigar Crater Row Activity
The Sundhnukagigar Crater Row has experienced a series of volcanic eruptions beginning in December 2023. Below is a timeline of these events:
December 18–21, 2023
The 2023 Sundhnukagigar fissure seen from a helicopter on the first night of the eruption.
The first of the most recent Sundhnukagigar eruptions started on December 18th near Hagafell, northeast of Grindavik. Lava sprays reached a height of over 328 feet (100 meters). The lava flowed much faster than previous disruptions, covering 3 km within one hour, reaching the outskirts of Grindavik. Over the first two days, the lava field surrounding Sundhnukagigar reached 4 square miles (3.7 km).
January 14–16, 2024
A second eruption began early January 14th by Hagafell Mountain near the Sundhnukagigar Craters, damaging three houses on Grindavik's edge, but the rest of the town remained unharmed. This marked the start of the 2024 Sundhnukagigar eruptions.
February 8–9, 2024
The start of the 2024 February eruption of Sundhnukagigar craters.
The February 8th eruption started less than a mile (1 kilometer) north of Grindavik, in the same area as the December eruption. It impacted roads and hot water supply infrastructure.
March 16–May 9, 2024
The lava of the 2024 March eruption flowed toward the Grindavik barriers and the Grindavikurvegur road.
The fourth eruption began on March 16th northeast of Hagafell. Initially presenting as a row of fissures, the activity later concentrated into a single crater. This eruption became the longest in the series, concluding on May 9th.
May 29–June 22, 2024
The fifth eruption started on May 29th following intense seismic activity. It featured a 3.4-kilometer-long fissure, with lava flows impacting Grindavik and Nesvegur roads.
August 22–September 5, 2024
The sixth eruption began on August 22nd, north of previous eruption sites. It was the largest in the series.
November 20–December 9, 2024
The seventh eruption began on November 20th and lasted until December 9. It caused damage to the parking area of the Blue Lagoon, but other infrastructure was safe behind protective barriers.
April 1st, 2025
The newest chapter in the Sundhnukagigar eruptions series started on the morning of April 1st, 2025. This 8th eruption started with an unusual number of small earthquakes that could be felt throughout Grindavik, with some being felt in the Capital Area.
Lava broke through the surface around 9:30 AM, emerging from the same area as previous Sundhnukagigar eruptions. For a time, there were concerns it might reach Grindavik, but the eruption quickly lost intensity. By the following day, activity had largely subsided, and no damage to infrastructure was reported.
Despite the eruption calming, the region continued to experience minor earthquakes, sparking speculation about the potential for renewed volcanic activity. While no further eruptions have occurred so far, magma continues to accumulate underground, suggesting that future eruptions remain likely.
Travel in Iceland remains unaffected, and Keflavik International Airport continues to operate normally.
Impact of the Sundhnukagigar Eruptions
The Sundhnukagigar eruptions have covered over 12 square miles (20 km) in fresh lava. Infrastructure damage in Grindavik has been severe, with residents forced to evacuate. However, nature is very skilled at healing itself over time. As lava reshapes the landscape, it eventually breaks down and creates new soil for plant life and moss to grow.
With Iceland's world-class monitoring systems and quick-response infrastructure, visitors are kept well-informed and safe. That means you can still enjoy the beauty and magic of Iceland, with only the immediate surrounding area of Sundhnukagigar Craters temporarily off-limits.
Evacuations and Infrastructure damage
The February 2024 Sundhnukagigar eruption seen from a safe distance. Photo from Wikimedia, Creative Commons, by Steinninn.
Thanks to the signals from seismic activity, scientists are able to predict when an eruption will take place, though the notice period tends to be different with each eruption. In previous events, the lava has flown over roads leading in and out of Grindavik. Some homes and buildings sustained damage. The famous Blue Lagoon Geothermal Spa is usually closed temporarily for each eruption.
Many were concerned about the Svartsengi Geothermal Power Plant, a major power and heating facility supplying Reykjavik and the peninsula. However, protective barriers have been set up, and lava has never reached the plant.
Impact on Grindavik and Recovery Efforts
Lava flow from the February 2024 Sundhnukagigar eruption reached the Grindavik road and the main Reykjanes hot water pipe.
In the aftermath of the Sundhnukagigar eruptions, more than 60 buildings have been deemed uninhabitable, including parts of a nursing home, an elementary school, and a gymnasium — all compromised by ground fissures.
Efforts to restore Grindavik has involved mobilizing dozens of electricians and plumbers to conduct critical repairs. Specialized teams addressed ground fissures and filled cracks to stabilize the area.
The Icelandic government and major banks offered financial relief, including:
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Waiving interest on housing loans
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Providing wage assistance to local businesses
Grindavik Reopens (with restrictions)
In October 2024, Grindavik was officially reopened to the public, though certain hazardous zones remained restricted. However, the town has temporarily closed again because of the April 2025 Sundhnukagigar eruption.
Today, authorities still monitor seismic activity and ground deformation to anticipate future disruptions.
Previous Eruptions on the Reykjanes Peninsula
After several centuries of rest, the Reykjanes Peninsula began showing signs of volcanic activity, which resulted in numerous eruptions and signaled a new volcanic cycle for the system. Rather than the cone-shaped volcano you may picture, these were fissure eruptions — long cracks emitting lava rather than a single crater.
Fagradalsfjall Eruption (March 2021 – September 2021)
The Fagradalsfjall eruption of 2021 began on March 19, 2021, in the Geldingadalur Valley. It was the first eruption on the Reykjanes Peninsula since the 13th century. The eruption produced slow-moving lava flows that did not threaten nearby infrastructure. It became a major tourist attraction and a hot spot for volcano tours.
Second Fagradalsfjall Eruption (August 2022)
While the first eruption lasted six months, the 2022 eruption of Fagradalsfjall lasted under three weeks. It occurred within the same volcanic system, but in the Meradalir valley, near the original eruption site. The flow of lava was more intense in this eruption, supporting the idea that the Reykjanes peninsula had entered a new volcanic cycle.
Thousands of tourists came to see the lava flow, and there were no significant disruptions to towns or roads. After the flow halted, seismic activity remained high, predicting future disruptions in the coming years.
Litli-Hrutur Eruption (July 2023)
The third eruption on the Reykjanes peninsula lasted about a month and occurred north of the previous eruptions. The lava flow was much more intense. In its first 48 hours, it produced more lava than the 2021 eruption produced in its entire first month.
Though no infrastructure was affected, Icelandic authorities began issuing warnings of dangerous gases and unpredictable lava flows. Seismic activity remained high after the new lava flows stopped, signaling that magma was still building up underground.
Predicting Eruptions in Iceland
Volcanic eruptions do not happen out of nowhere. They occur due to the accumulation of magma underground. This accumulation of magma produces earthquakes that tell experts what to expect and when.
Organizations like the Icelandic Meteorological Office (IMO) and others track this activity to provide early warnings and lower the risk of its effects. Learn more about earthquakes in Iceland in our guide.
Key Methods for Predicting Eruptions
There are a variety of methods for predicting volcanic eruptions and activity. By combining data from different monitoring methods, scientists can develop models to forecast the likelihood and timing of volcanic eruptions and provide warnings to communities at risk. However, predicting volcanic eruptions remains a challenging task, and no method is 100% accurate.
Photo from Regína Hrönn Ragnarsdóttir. An old seismometer at the Earthquake Center in Kopasker Town.
Seismometers (Earthquake Monitoring)
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Detect earthquakes and magma movement
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Before an eruption, earthquakes become stronger, more frequent, and shallower
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Thousands of small, shallow quakes often signal that magma is rising
GPS Stations (Ground Deformation Tracking)
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Measure tiny shifts in the landscape
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Rapid uplift (as seen near Grindavik before the Sundhnukagigar eruptions) indicates magma intrusion
Satellite Radar Imaging
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Tracks large-scale ground movements
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Before-and-after radar images map magma buildup and predict lava paths
Infrared Cameras (Heat Detection)
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Detect heat changes underground to trace magma flow
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A sudden temperature increase near a fissure can signal an imminent eruption
Water System Changes
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Hot springs warming up, wells drying, and glacial melting can indicate magma movement
This combination of technology, planning, expertise, and dedication has resulted in a solid emergency-ready infrastructure. Iceland’s scientists and authorities monitor the situation to keep people safe, monitor gas levels, and protect infrastructure.
How to Experience Sundhnukagigar Volcano
Though experts are still monitoring the Sundhnukagigar craters and the Reykjanes Peninsula for volcanic activity, the region offers exciting activities.
Guided Day Tours
Helicopter tours fly travelers over recent disruption sites to provide views of the craters, lava fields, and geological formations from above. You can get a peek at this livestream of the eruption site.
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Scenic 1-Hour Helicopter Tour by the Latest Volcanic Fields in The Reykjanes Peninsula
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30-Minute Sightseeing Helicopter Tour by Lava Formations in the Reykjanes Area
There are also hiking tours available in the area that bring you to the area around Fagradalsfjall Volcano. You may be able to see Sundhnukagigar Craters in the distance. The area around Sunhnukagigar is still closed for safety:
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Guided Afternoon or Evening Hike Tour to the Reykjanes Volcano Area
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Hiking Tour to the Reykjanes Volcano Area with a Blue Lagoon Admission
Self-Drive Tours
These convenient self-drive tour packages highlight Iceland's incredible volcanic landscapes while you explore with the freedom of a rental car.
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10-Day Self-Drive Tour of the Ring Road and Snaefellsnes Peninsula
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1-Week Summer Self-Drive Tour of the Ring Road and Golden Circle
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1-Week Self-Drive Tour of West and South Iceland with the Golden Circle
Vacation Packages & Bundles
It's easy to plan a whole vacation by booking a complete vacation package, or making the most of your trip with a bundle tour. These highly rated options will bring you up close to Iceland's fiery nature.
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7-Day Summer Vacation Package with the Inside the Volcano Tour and Jokulsarlon Glacier Lagoon
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3-Day Northern Lights Winter Stopover in Reykjavik with the Golden Circle and Blue Lagoon
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3 in 1 Bundle Discount Tours of Golden Circle, Ice Tunnel & Inside a Volcano
What to See Near the Sundhnukagigar Crater
Staying in Grindavik is currently not recommended, so consider checking out these opportunities to stay in Reykjavik, which is just a short drive away.
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Blue Lagoon: This renowned geothermal spa remains a major highlight, providing a unique bathing experience in mineral-rich, warm waters.
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Gunnuhver Hot Springs: Located nearby, these geothermal hot springs offer a glimpse into Iceland’s geothermal activity, with bubbling mud pools and steam vents.
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Hiking opportunities: Though the surrounding area of the Sundhnukagigar Craters is closed, the Reykjanes Peninsula boasts numerous trails for hiking, allowing visitors to explore the rugged beauty of the region.
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The bridge between continents: You can see where the North American and Eurasian tectonic plates are diverging at the Bridge between the Continents, just a short drive from the Sundhnukagigar Crater Row. The trails here weave through the crater row and adjacent lava fields.
Sundhnukagigar Volcano FAQs
Interested in learning more about the Sundhnukagigar Volcano and the Reykjanes Peninsula? Check out these frequently asked questions.
What is Sundhnukagigar?
Sundhnukagigar is a volcanic fissure system on the Reykjanes Peninsula in Iceland. It is part of the Svartsengi volcanic system and has experienced increased seismic activity in recent years.
Is Sundhnukagigar an active volcano?
Yes, it is an active volcanic system. Recent eruptions and seismic activity indicate that it is experiencing a period of increased unrest.
Is it dangerous to visit Sundhnukagigar?
Yes, visiting the area can be dangerous due to volcanic gas emissions, unstable terrain, and the risk of sudden eruptions. Authorities closely monitor the area and issue warnings accordingly.
How is Sundhnukagigar monitored for future eruptions?
Scientists use seismic data, GPS measurements, and gas emissions analysis to track magma movement and predict potential eruptions. The Icelandic Meteorological Office (IMO) provides updates and warnings.
What should visitors do if an eruption occurs?
If an eruption occurs, follow official guidance from the Icelandic authorities. Avoid restricted areas, monitor emergency alerts, and be prepared for possible evacuations if in nearby towns.
Learn More about Volcanoes in Iceland
The Sundhnukagigar eruptions serve as a powerful reminder of Iceland's dynamic landscape. While the area remains under careful observation due to ongoing activity, the broader Reykjanes Peninsula offers a fascinating glimpse into the forces shaping our planet.
Whether through helicopter tours, hikes in the surrounding areas, or visits to nearby attractions like the Blue Lagoon, there are still ways to experience the awe-inspiring power of Iceland's volcanoes. To learn about other top volcanic activities and sites across the country, be sure to check out our article on the Top Volcanic Activities in Iceland.
