This article is based on an episode of The Adventure Story Podcast, where I chase legends, uncover history, and ask the questions that sometimes get ignored. Listen below, or wherever you get your podcasts.
The Underground Superhighway: Could Ancient Lava Tubes Connect the Continents with Dave Bartell
Beneath your feet, right now, there may be a tunnel. Not a man-made one — no Victorian brickwork, no concrete lining — but a vast natural passage carved by flowing lava millions of years ago, stretching for distances that would make your eyes water. And here is the question that has been rattling around in my head since I spoke to author Dave Bartel for the Adventure Story Podcast: what if those tunnels are bigger, and reach further, than we have ever suspected?
Because if they do, they change everything we think we know about how the ancient world moved.
What Is a Lava Tube?
When a volcano erupts, lava flows outward across the surface. The outer edges of that flow cool first, hardening into a crust of solid rock. But beneath that crust, the molten lava keeps moving — draining away, carving through the solidified shell, and eventually leaving behind a hollow tube. The result is a natural underground tunnel, sometimes metres wide, sometimes kilometres long, sometimes branching into networks that run beneath entire landscapes without a single visible sign on the surface.
The largest known examples are extraordinary. The Thurston lava tubes on the Big Island of Hawaii and the Undara tubes in Australia — which run for over 160 kilometres — are among the most impressive, but as Dave points out, these are simply the ones we have found. “The biggest are the Thurston lava tubes in Hawaii, the Undara tubes in Australia, and there are lots of smaller ones all over. So it’s plausible you could have longer sets of tubes.”
And that plausibility is where the story really begins.
“Beneath where each of us is sitting right now, there could be a network of tunnels that have been undiscovered,” Dave says, “because you don’t know how deep they could go. If you hadn’t looked for them, or that area hadn’t been excavated for any other reason, you just wouldn’t know.”
He is right. And that thought, once it takes hold, is genuinely difficult to shake.
The Roman Connection
Dave’s novel Roman Ice is built on a premise that follows this idea to its logical — and thrilling — conclusion. What if a network of lava tubes runs beneath Europe? What if the Romans found these passages and used them to move through the landscape in ways that left almost no surface trace?
It would explain something that has always quietly nagged at historians: how a civilisation without modern transport managed to project its influence across such vast distances. We know Roman artefacts have been found across Scandinavia, generally attributed to trade routes through Germania. But what if some of that movement happened underground, through passages that have since been sealed, collapsed, or simply never found?
“I like to think that Rome had explorers like any other culture,” Dave says. “You’ve got your armies and your traders, but you’re going to have folks who go out beyond the boundaries of the empire to find out what’s there. Romans mined everywhere they went — so it’s possible.”
Dave’s protagonist is an archaeologist whose entire mission is built around proving that this network exists. The Roman scrolls describe it. What he doesn’t have is the entrance. “They’ve theorised this, but they’ve never been able to prove it,” Dave explains. “They have these old Roman scrolls that say the tunnels are there — but where’s the front door?”
It was a BBC headline — Roman coins found in Jersey — that first sparked the idea. “I started thinking, could the Romans have reached North America? Well, the Romans weren’t great sailors. Then I started thinking about what if there was a way they could move underground — and somewhere along there I discovered lava tubes.”
As it turns out the article was referring to the island of Jersey in the English channel, not Jersey in America, but Dave’s imagination was already running.
Iceland: The End of the Road
If you follow the logic of a subterranean lava tube network beneath Europe, and accept that Roman explorers were the kind of people who pushed into the unknown, the question becomes: how far could they have gone?
Dave’s answer is Iceland. The Romans pushed their known world as far as Caledonia — what we now call Scotland — and beyond that lay the genuinely unknown. “Germania, Gaul, Britannia were well-known parts of the Empire,” Dave says. “But beyond Caledonia, that’s an unknown place. So what could you find there? Someplace really interesting and remote that if a discovery was made, it would cause big question marks — what was going on? Why did they get here?”
Iceland, sitting in the North Atlantic as one of the most volcanically active places on earth, is itself riddled with lava tubes. If a continental network of tubes existed, it would be a natural terminus — a remote, extraordinary destination reached not across the open ocean but through the earth itself. “Nobody really lived there until about the eight hundreds,” Dave notes. “It’s both physically, geologically, and culturally interesting — fascinating place to have a story.”
Beyond Earth
Here is where the lava tube story takes its most unexpected turn. Scientists now believe that lava tubes exist not just on Earth, but on the Moon and on Mars. The tubes on these bodies, formed in lower gravity, may be orders of magnitude larger than anything we have found on Earth.
“It’s even plausible that they’re on the moon,” Dave says. “They say if they’re on Earth, they’re on Mars, they’re on the lunar surface — which were volcanically active. There’s even a theory developing that we could land on the moon, use these lava tubes, seal them off with air, and build habitats for a lot less money than above surface.”
The thought that the same geological phenomenon that might have carried Roman explorers beneath the European landscape could one day shelter human beings on the Moon is, to put it mildly, a lot to sit with.
The Scrolls That Couldn’t Be Read
The other historical thread running through Roman Ice connects to a real and recent breakthrough. When Vesuvius erupted in 79 AD, it buried the nearby town of Herculaneum along with the contents of a wealthy Roman’s library — hundreds of scrolls, carbonised so thoroughly that any attempt to unroll them crumbled them instantly.
For nearly two thousand years those scrolls sat unread. Then researchers developed a technique using 3D scanning combined with AI to detect the faint raised surface of ink on papyrus and reconstruct the text without ever physically touching the document. Dave had put exactly this technology into his novel years before it became reality.
“I was cracking up when I first saw this prize handed out last year,” he says. “It’s like, oh, there’s this thing I put in my book that’s become a reality now. The old reversal of fiction stranger than truth.”
A Lost Library Worth Finding
When I asked Dave where he would go if he could lead a real expedition, his answer surprised me completely: the Lost Libraries of Timbuktu. Between the 13th and 17th centuries, Timbuktu was one of the great intellectual centres of the world. “This was the intellectual hub of the world,” Dave explains, “when most of Europe was mired in medieval thinking. You’ve got great thinkers from Persia, Egypt, Spain, Morocco joining up with Malian, Berber, and Arab scholars — a fusion of African, Arabic, and Greek ideas all in one place, creating this vast library.”
Most of that knowledge is thought lost. But as Dave puts it: “Ancient knowledge is lost — most everything ever written is gone. But some of it might still be there.”
“We all know the lost library of Alexandria,” he adds, “but here’s this other one, on this massive continent, that we don’t think about as much.”
I told Dave on the spot that I’d join him on that expedition. I meant it.
You can find Roman Ice and Dave’s other books on Amazon, and a free novella at davebartel.com.
If you enjoyed this, the full conversation with Dave is available on The Adventure Story Podcast — find it wherever you get your podcasts. And if you’d like to join the Adventure Society, my weekly newsletter covering real-world adventures, new books, and podcast updates, head to lukerichardsonauthor.com/adventuresociety.
