By Chris Ayliffe, Arctic Meta
Somewhere beneath Iceland’s pristine glaciers, monsters sleep (metaphorically speaking).
Not mythical trolls or elf kings (though we have those too, of course), but churning chambers of molten rock just waiting for the right moment to stir.
Subglacial volcanoes have been a constant in Iceland for as long as we’ve known, though I can’t entirely vouch for having personally watched the full lifespan of the Mid-Atlantic Ridge.
They’re mysterious, unpredictable, and occasionally loud enough to ground half of Europe’s flights (and give you something impossible to pronounce at the same time).
This is your guide to Iceland’s most explosive secrets, the ones lurking quietly beneath the ice. At the same time, you consider that extra adrenaline-pumping snowmobile tour above Katla (a beast of a caldera).
Iceland Glaciers Fiery Secrets
Most countries have mountains. Iceland has mood swings (and I’m not just talking about the snowstorms that accompany our crazy weather).
One moment, it’s all stillness and serenity. The next, you’re watching fire explode like the beginning of a newer and more incredulous Marvel film through a glacier.
That’s the kind of surprise only Iceland can deliver from time to time.
Subglacial volcanoes are part of Iceland’s not-so-secret identity.
These fire-breathers live beneath thick ice caps, brooding in the dark like something out of Norse mythology (no Chris Hemsworth in sight).
The country straddles the Mid-Atlantic Ridge. It’s tearing itself apart, quite literally.
And in the chaos, volcanoes are born beneath the glaciers.
Why Iceland Is a Volcanic Hotspot
Blame it on the tectonic plates.
Iceland sits directly over the boundary where the North American and Eurasian plates are moving in opposite directions.
To add fuel to the fire (pun intended), there’s also a hotspot underneath.
The result has delivered over 30 active volcano systems across the island.
Some are very much out in the open (ahem, Hekla which you can see from our lodges in the South). Others are sneakier, hiding beneath glaciers, and these ones can be particularly explosive.
The Unique Phenomenon of Subglacial Volcanoes
Most volcanoes erupt and leave behind lava flows, craters, and ash.
Subglacial volcanoes add an extra ingredient: several hundred metres of solid ice.
When they erupt, the heat melts the ice above, causing dramatic floods and, occasionally, creating ice caves and strange, otherworldly formations, some of which you can visit such as Katla ice cave.
They’re Iceland’s version of a pressure cooker, only with magma (so, yes, they would easily melt a pressure cooker).
How Do Subglacial Volcanoes Work?
It’s not exactly a campfire story when the fire is buried under a kilometre of solid ice.
But Iceland’s subglacial volcanoes have their own way of heating things up.
They don’t explode like their tropical cousins.
Instead they stew, boil, and simmer like a disgruntled Viking being ignored in a queue.
And then, when the pressure cooker (the magma one) hits its limit, they make sure the island remembers who’s boss.
What follows is rarely neat or predictable.
Sometimes it’s an eruption with ash clouds painting the skies grey, like that of the famous Eyjafjallajökull eruption in 2010.
Sometimes it’s a flood, bursting out from beneath the glacier like Iceland’s version of pulling the plug on a giant icy bathtub. I should mention a melty one at that too.
Unfortunately, these aren’t the kind of volcanoes that pose nicely for photos.
They’re the kind that make scientists fidget and travellers stare in awe, whilst pilots tend to get a few extra days or weeks off pending the scale of the ash cloud.
Here’s how the quietest volcanoes on Earth manage to cause some of the loudest trouble.
The Clash of Fire and Ice (When Glaciers Interact with Volcanoes)
When magma rises under a glacier, it doesn’t immediately burst forth in flames.
First, it meets its icy rival. The intense heat from below starts melting the thick glacial ice layer by layer.
What begins as a quiet melt quickly turns into a volatile brew.
Steam forms in pockets, trapped between rock and ice with nowhere to go.
As the pressure climbs, so does the tension.
Eventually, like a bottle of shaken-up coke (probably similar to that one I keep leaving in the back of my Peugeot), something has to give.
That pressure can cause the glacier to crack or burst from within, triggering an explosive release.
This can lead to ash, gases, and sometimes lava which is violently ejected, punching through the ice and sending great plumes into the atmosphere.
These eruptions are capable of shaping the terrain, disrupting air travel, and definitely get the geologists all over Facebook reels (or at elast in my feed).
Jökulhlaups: Glacial Floods That Emerge From Below
If you thought Icelandic weather was unpredictable, meet the jökulhlaup (glacial run in English), a glacial outburst flood which can even happen regularly in summers in Iceland, even without an eruption.
These floods are caused when subglacial eruptions melt vast reserves of ice, creating pressurised lakes beneath the glacier’s surface.
As the meltwater builds, it begins to lift or erode the glacier from below, forming unstable tunnels or ice dams.
At some point, the dam gives way. Often this happens without much notice (like the electrics on my Peugeot).
Then you get an explosive release of water that surges across the land at increidble speed.
We’re talking about torrents capable of carrying house-sized boulders and submerging the roads along the south coast of Iceland very quickly.
Historical jökulhlaups have altered Iceland’s landscape permanently, creating new floodplains and reshaping river systems in a matter of hours.
Monitoring stations now dot key glacial areas, giving authorities enough lead time to issue evacuation alerts.
For locals (especially those in places like Vík), this is just part of life.
For instance, farmers need to always keep one ear to the ice, waiting for the next rumble from below.
To see a cool example of this, you can pull over on your way to Skaftafell where a previously washed up bridge has been kept for travellers to take a closer look at (and, yes, you can climb it).
What Makes Subglacial Volcanoes So Dangerous?
They’re silent.
They’re slow to reveal their hand (very Le Chiffre from Casino Royale if you happen to be a Bond fan).
And when they do erupt, it’s often without much warning. It can be just a sudden shift, then chaos, but this is 2025 so you can be confident in knowing there is a lot of tech monitoring everything from earthquakes to lava intrusions, ground elevations and more 24/7.
Unlike their tropical counterparts that offer lava rivers and fireworks displays, these ones are like the northern winds: cold, cryptic, and dangerous when underestimated.
Add to that the threat of jökulhlaups, choking ash clouds, airborne debris, and the occasional collapse of glacier caves, and you’ve got a geological ambush wrapped in a frozen disguise.
Even the landscape can change within hours in more dramatic scenarios. Though the scale and severity, as well as the duration of any eruption cannot be fully expected in advance.
These aren’t the kind of volcanoes you casually hike up.
They demand respect, distance, constant monitoring, and very good weather insurance.
But, remember, you are visiting the land of fire and ice, so this is just a moment when your trip could get extra exciting.
Iceland’s Most Famous Subglacial Volcanoes
Not all volcanoes are created equal (and I’m not writing that to make them feel better).
Some prefer to hog the spotlight, while others brood quietly beneath the ice, waiting centuries to make an entrance.
These geological celebrities have shaken the skies, carved out new land, and even shut down Europe for a week (much to the annoyance of one blunt Scotsman if memory holds).
Katla: The Sleeping Giant Beneath Mýrdalsjökull
Katla is overdue.
Every local, and seismologist, (and sheep) in the area knows it. But, don’t stress it, they are all sleeping restfully whilst keeping tabs on any rumblings.
Tucked beneath the thick ice of the Mýrdalsjökull glacier, Katla has a reputation that precedes her.
Her eruptions are not polite geological hiccups, they’re full-scale, landscape-altering events.
When she last erupted in 1918, the jökulhlaups that followed didn’t just rearrange a few rocks; they sent glacial torrents thundering to the sea, carving out new coastline in their wake.
Since then there’s been a relative radio silence other than some earthquakes beneath here and there. This can make scientists twitch, particularly when they know that Katla likes to erupt roughly every 100 years (yes, we are overdue by 7 years at the time of writing).
She’s been rumbling in her sleep, occasionally shifting, occasionally sending up a puff of sulphur-scented breath.
But still no eruption.
It’s not a question of if Katla will erupt again.
It’s when.
And when she does, Iceland’s south coast will be reminded once more of what lies beneath its icy skin.
Grímsvötn: Iceland’s Most Active Subglacial Volcano
Hidden under the icy grip of Vatnajökull, Grímsvötn is Iceland’s most prolific volcanic troublemaker.
It erupted in 2011, blasting a plume of ash over 20 kilometres into the atmosphere and disrupting air traffic across the region (not just because the Eyjafjallajökull from 2010 put this on trend).
This wasn’t a one-off tantrum.
Grímsvötn has a long history of frequent eruptions, often occurring every decade or so.
What makes it particularly fascinating (and mildly terrifying) is the massive subglacial lake beneath its surface.
This lake acts like a ticking clock, filling with meltwater from geothermal activity and occasionally triggering powerful jökulhlaups when the pressure becomes too much.
Volcanologists monitor it obsessively using GPS, radar, and glacial sensors, all while glancing nervously at their inboxes.
Because when Grímsvötn stirs, it rarely whispers (a similar description I’ve been told about my own snoring habits after a few wines).
Bárðarbunga: A Firestorm Beneath Vatnajökull
Not to be outdone, Bárðarbunga decided to throw its own party in 2014, and it was no small gathering.
That year, it produced the largest lava flow Iceland had seen since the 18th century, blanketing the Holuhraun lava field with more than 85 square kilometres of fresh volcanic rock.
The eruption lasted six months literally remade parts of Iceland’s map.
This colossal system, tucked beneath the Vatnajökull glacier, is part of a vast interconnected network of fissures, calderas, and subglacial plumbing that extends across the entire highlands.
You can think of it as Iceland’s subterranean labyrinth, only instead of minotaurs, you get magma, which is even less friendly.
Its activity remains under close surveillance by scientists, who still aren’t entirely sure what surprises it may be cooking up next.
Eyjafjallajökull
You might not be able to pronounce it.
But you definitely remember it.
Eyjafjallajökull erupted in 2010 and became an overnight global sensation for all the wrong reasons.
The eruption sent a plume of ash into the atmosphere that drifted over mainland Europe, grounding over 100,000 flights and stranding millions of passengers.
Suddenly, Iceland was at the centre of every weather report, aviation update, and panicked travel blog (none of mine, however).
News anchors stumbled hilariously over the name while airlines scrambled to explain why they couldn’t fly through volcanic dust.
Though not the most powerful eruption in Iceland’s history, it was one of the most disruptive, proving that you don’t need to be massive to make a mess.
Eyjafjallajökull reminded the world that in Iceland, even a modest subglacial volcano can punch way above its weight class, and knockout a continent (pun very much intended on this occasion).
How Scientists Monitor and Track Hidden Volcanoes
I’ll start with the good news first: Icelandic scientists are some of the best in the world when it comes to volcanology, and they take volcano-watching as seriously as a Viking took his raiding.
They use a full arsenal of modern tools to track every twitch and tremble beneath the ice: GPS stations to detect ground movement, seismic sensors to capture the tiniest underground grumbles, satellite imagery to monitor glacier surface changes, and thermal imaging to catch heat sneaking through the ice.
They even drill through glaciers (yes, drill through tonnes of ice) just to reach and analyse subglacial lakes that may be holding back pressure.
It’s equal parts science, obsession, and a pinch of luck.
And it’s absolutely vital to keeping both locals and visitors safe when Iceland decides to get fiery again.
Is Eruption Forecasting a Science or an Art?
Both.
There are models, measurements, and calculations.
Seismic data is constantly analysed, GPS stations track the smallest ground movements, and glacial melt rates are observed for signs of trouble.
But even with these scientific capabilities, predicting when a volcano will erupt remains one of Earth’s trickiest guessing games. Not even Stephan Hawkin could tell you that.
It’s a bit like trying to predict when a dodgy Wi-Fi connection might drop during a Zoom call. And by that I mean it’s inevitable, mysterious, and never convenient.
Some volcanoes offer weeks of warning with increased seismic activity and swelling ground.
Others erupt with barely a grumble, catching even the most experienced volcanologists by surprise.
Forecasting eruptions requires a blend of hard data, historical patterns, and what can only be described as educated gut instinct (though they are bold to use the latter in a live news broadcast).
And in Iceland, that instinct is sharpened by centuries of living side by side with lava.
You can think of the scientists here as the modern-day rune readers of the Earth’s crust (a great idea there for a bread company slogan).
Can You Visit These Subglacial Wonders?
It’s one thing to read about magma lurking beneath the ice.
It’s another to stand on top of it with crampons strapped to your boots and your breath fogging in the north Arctic air, knowing full well that the sleeping giant beneath your feet once changed the course of a river.
The good news is you don’t need to be a volcanologist or wear a lab coat to get close.
Thanks to Iceland’s uniquely active geology, there are few places on Earth where you can safely interact with such powerful natural forces up close.
Whether you’re peering into glittering ice caves shaped by geothermal heat or walking trails traced by some of the ancient lava flows like Laki, these experiences offer a visceral connection to the island’s fiery foundation.
No eruptions required. Just curiosity, warm layers, a decent guide, and perhaps a slight disregard for your comfort zone, in the best possible way.
Glacier Hikes and Ice Cave Tours
The short answer? Sort of.
You won’t be trekking across lava flows on an erupting volcano (unless you have a death wish or a Netflix documentary deal in mind).
But you can explore the glaciers that conceal these fiery giants all-year round (with a guide, I’ll add).
Beneath the surface, where ice meets geothermal heat, nature has carved out surreal passageways and cathedral-like caves of glowing blue which change by the season with the creeping (not creepy) movement of the glacier.
From guided glacier hikes that take you across creaking ice fields, to ice cave tours where you can literally walk through sculpted frozen tunnels formed by volcanic heat, these experiences offer an eerie and exhilarating glimpse into Iceland’s subglacial world that you won’t want to miss.
Some tours even include educational insights from local guides who blend folklore with geology, so you can learn what you’re walking on and what ancient fire it might be hiding (for sure is).
Winter is best, when the caves are at their most stable, the colours more vivid, and the crowds are generally smaller (don’t go and visit an ice cave in summer, unless it’s Katla ice cave which is open all-year round).
Plus, nothing says “I survived Iceland” quite like crawling through a glacier that sits above a dormant volcano. You can even snowmobile across Katla (I’ve done it and I can confirm I am still alive).
Volcanic Landscapes You Can Actually Explore
Not every volcano hides.
Some wear their scars with pride.
Drive along the South Coast and you’ll pass sprawling lava fields that once glowed red hot, now cooled into twisted black formations, some said to be petrified trolls (look out for the two trolls in love high up along the Ring Road around 10km west from Jökulsárlón).
The region is also dotted with moss-covered craters, strange ridgelines, and jagged plateaus which are all remnants of eruptions that reshaped the land long before anyone was around to write about it.
You can visit the area around Eyjafjallajökull, where farms still operate in the shadow of a volcano that grounded half the world’s flights a decade (point five) ago.
Or explore the highlands near Vatnajökull, where raw wilderness and ancient lava flows stretch as far as the eye can see.
It may look peaceful now, but there’s an energy here which I can only describe as a restless tension beneath your feet, as if the land itself remembers everything it’s been through (geology therapy at work).
You might not see an eruption. But you’ll feel the raw power underfoot, in every crack, ridge, and gust of sulfur-scented wind (and shower water).
What to Know Before Going
Check tour operators for safety ratings, recent reviews, and proper certifications. If their website features more comic sans than contact information, maybe keep scrolling.
Listen to guides. Always. They’re trained, experienced, and generally better at not falling into crevasses than you.
Don’t wander off. Even if you see something shiny, suspiciously glowy, or Instagram-worthy. Glaciers are not playgrounds, and volcanoes don’t care about your follower count (neither do your followers come to think of it).
Dress for the weather, carry snacks and a bottle of water, and always tell someone where you’re going.
And if you’re staying nearby, make sure it’s somewhere that offers not only incredible views and glass walls but also a private hot tub, fluffy blankets, and strong Wi-Fi just in case you want to check if Katla’s woken up before bed (hint hint).
Iceland’s Fiery Heart: A Land of Constant Creation
Iceland isn’t finished forming. Not even close.
New land bubbles up through fissures, glacial tongues creep and retreat like slow-moving dragons, and volcanoes quietly plan their next spectacle away from prying eyes.
Glaciers reshape, collapse, flood, and sometimes help to get international media attention with the explosive reaction with magma.
Lava becomes entire valleys, sculpted plateaus, and then much later, fields of moss which you’re not allowed to stand on.
Remember, Iceland is a living, breathing force of nature that’s constantly growing. But, unfortunately not at a pace that you’re likely to see too much expansion (Reykjanes has seemingly asked me to hold it’s beer to comeback at my last remark).
You’re not here to see something old.
You’re witnessing Earth mid-sentence, telling a story in fire and ice.
It’s humbling, awe-inducing, and occasionally enough to make you double-check your travel insurance. What’s more wild than that?
The Panorama Glass Lodge: Sleep Under the Stars, Over the Fire Below
Now that you know what’s underneath the ice, it’s time to see it for yourself.
The Panorama Glass Lodge offers front-row seats to Iceland’s volcanic drama.
From the comfort of your glass-walled cabin, you can stargaze over the icy horizon, knowing a volcano might be muttering below the surface.
Our lodges in South Iceland are nestled near glaciers, black beaches, and old volcanic paths with views of the highly active Hekla from within.
Conversely, our West Iceland family lodges offer space, serenity, and the occasional distant rumble (usually very distant).
Enjoy your private sauna as you listen to the wind whip across volcanic plains.
Or sip something you picked up from the local Vínbúðin in your private hot tub as the Northern Lights perform their usual tricks above.
And if you’re lucky, the only thing erupting will be your excitement levels (cringe, I know, but it has been a solid few hours of thinking up volcano puns for me).
Final (Chilled not Fiery) Thoughts
Subglacial volcanoes are equal parts beautiful and terrifying.
They’re part of what makes Iceland… well, Iceland.
You won’t find them anywhere else quite like this.
And while they may lie beneath the surface, their story rises above it.
Come experience it from the best seat in the country.
Book your stay at the Panorama Glass Lodge and witness Iceland’s frozen fire from a very comfortable bed with an unbeatable view (not a bad place to see some fiery apocalypse I think you’ll find).
Because the only thing more thrilling than a volcano is a volcano you can safely admire in your pyjamas.