‘“See the great fins!” shouts the professor. “See the air and water sprouting from the blowholes!” We stand, shocked, astonished, terrified at the sight of a shoal of sea monsters, the smallest of which could split our raft with a snap of its teeth.’ - Journey to the Centre of the Earth by Jules Verne

A jet of water erupts off the starboard side of our boat, and the spray splashes the deck. There's barely time to understand what's happening before a flash of silver whale's skin breaks the surface, dips beneath a wave and plunges down to the dark fathoms of the North Atlantic. Out here, within sight of Reykjavík, whale spotters and whaling boats scour the seas for these mighty beasts. The minke whale, notorious for its bad breath; the blue whale, whose tongue alone outweighs an African elephant; and the leaping humpback whale, all have patrolled the depths beneath our boat.

These may not be the sea monsters Jules Verne describes in Journey to the Centre of the Earth, but Iceland is the setting for his famous novel. Verne's heroes - the eccentric Professor Lidenbrock and his long-suffering nephew, Axel - discover a clue encrypted in an old Icelandic manuscript that sends them to the island in search of a passage to the core of the planet. The adventure follows the characters as they navigate underground seas filled with prehistoric sea monsters, dodging lava flows and crossing bottomless chasms. The strange subterranean world that Verne describes isn't too far removed from the landscapes on the surface in Iceland. This, after all, is a place where lightning storms ravage volcano craters; where the ground can crack open and gobble up the farmland; where new islands have popped up overnight in the surrounding seas.

Pulling into Reykjavík harbour, just as Verne's characters did, it seems remarkable that anyone could make their home in this forbidding land. Huge cliffs loom all around, looking like they might lurch forward at any moment and push the tiny town into the sea. Reykjavík sits on the edge of the Arctic Circle with a defiance that would make its Viking founders proud. In the summer, revellers flock to the streets for the runtur - the bar crawl famous for its excess and irreverence (one nightclub even has the faces of failed Icelandic bankers plastered over its urinals). In the winter, the crowds disappear inside cosy cafés, while the corrugated-iron houses shudder in thundering Arctic winds.

Guarding over the city is Hallgrímskirkja, the church where, from high up in the bell tower, the outline of Snæfellsjökull can just be seen. This snow-capped volcano, scarcely visible behind a veil of mist, was Professor Lidenbrock's destination - the mountain where an ancient riddle spoke of a crater at the summit that leads to the centre of the Earth. The volcano strikes an ominous presence on the horizon - one of countless sleeping giants in Iceland that might one day stir, sending torrents of fire, rock and ash raining down. Lurking in the fog, Snæfellsjökull seems to dare me to trace the footsteps of Verne's heroes - to scale its slopes and find out if the summit really does hide a gateway to a world beneath our feet.

'How can we know for certain that Snæfells isn't about to erupt? The fact that this monster has slumbered since 1229 does not mean that it will not wake. And if it does, what will become of us?' -Journey to the Centre of the Earth by Jules Verne

We are not talking about pregnant ladies,' barks the professor. 'We are talking about volcanoes; there is no due date - no timetable for an eruption.'

Professor Haraldur Sigurdsson is something of a celebrity in this remote corner of Iceland, a volcanologist who grew up in the shadow of Snæfellsjökull and who has set up a volcano museum in Stykkishólmur, his hometown. Little more than a cluster of timber houses huddled around a natural harbour, Stykkishólmur is one of the last staging posts before the Arctic Circle. Pacing the quay are sturdy fishermen with thick woollen jumpers and rambling beards. Seagulls stalk the rooftops - swooping down on discarded scraps of fish - but otherwise, signs of life here are scarce.

In the darkened hall of the professor's museum, paintings of volcanoes hang alongside antique geological instruments used by Verne's contemporaries. 'At the time Jules Verne was writing, some people believed the earth was hollow,' he says. 'For readers in those days, a trip to the centre of the Earth, with dinosaurs and cavemen, was quite plausible.' Not that geology has lost its sense of adventure: Professor Sigurdsson recounts how his helicopter was rocked by the sonic boom of exploding gas bubbles as he hovered over the crater of Eyjafjallajökull. The eruption that brought European airports to a standstill he shrugs off as barely a blip.

Haraldur Sigurdsson is touched by an eccentric genius common to Icelanders. Visitors to these parts might hear about the optician erecting homemade wax stalagmites in caves; the record producer building his own troll garden beside a waterfall; the adventurer who has tweaked a Soviet missile launcher to transport tourists across the Langjökull glacier (and who one day hopes to build a concert venue out of the ice at the top). There is something about this empty land of lonely roads and rusting barns that seems to breed a peculiar resilience in its inhabitants.

We step out into the daylight in Stykkishólmur, and birds are circling above as a boat leaves the harbour. The professor points to the huge white mass beyond the tiny town. 'Snæfellsjökull isn't dormant,' he says, 'it's just taking a break.'

'A sheet of snow gleamed on the slopes of these distant mountains... the peaks brazenly pierced the grey cloud to reappear above the shifting vapours like reefs, suspended in the sky...' - Journey to the Centre of the Earth by Jules Verne

From Stykkishólmur, the road winds along fjords and over mountain passes to the foot of Snæfellsjökull and up to Verne's fabled passage to the centre of the Earth. Driving towards the peninsula's tip, it's clear that human settlement has hardly made a scratch on this barren landscape. Horses watch the few cars speeding past with the attentiveness of spectators at a tennis match. Sheep amble the roads, meeting drivers with looks of horror. Nameless waterfalls tumble down from the plateau above, while the shadows of clouds dance across treeless slopes.

A dirt track leads to the summit and the mist thickens as we ascend. There's something hallucinatory about climbing these mountains - drivers on one road have talked of sensing an extra passenger in the back seat. Mystics, too, have flocked to the volcano, claiming it as one of the planet's seven sources of spiritual energy.

It was on the summit that Professor Lidenbrock and Axel made their camp, waiting for the shadow of a nearby peak to pinpoint the crater where they were to begin their descent. Following their route is easier said than done. Parked directly on top of the mountain is a vast Ice Age glacier that Jules Verne, who never visited Iceland, neglected to mention in his novel. Any crater would have to be buried deep beneath thousands of tonnes of dense ice, so it's difficult to know where to start looking.

I'm about to leave empty-handed when the clouds break and, as Verne wrote, it seems Snæfellsjökull has sprung straight up from the seabed. Here, Axel claimed he was so 'engrossed by the exalted rapture of these soaring peaks... I forgot who I was and where I was.' Expanses of black rock swoop down to the shore, where lighthouses look little more than golf tees perched on the cliffs. Despite their presence, a glance at a map reveals the surrounding cape is strewn The church at Ingjaldsholl, below the towering peaks of Snæfellsjökull, was built in 1903, though it houses some older tombstones and a wonderful painted wooden altarpiece with shipwrecks: Anne Dorothea in 1817, Solöven in 1857 and Brilliant Star in 1882.

Far below, on the peninsula's southern beaches, stands the Hotel Buðir, a place where Professor Lidenbrock's party passed through on their journey to Snæfellsjökull, and a popular retreat for Icelandic writers and artists. Night closes in as I descend the mountain. The reflections of shooting stars light up the saltwater pools around the hotel, and the glacier glistens a brilliant white in the moonlight.

While staying at the hotel in the 1960s, Icelandic author Halldór Laxness wrote Under the Glacier, a story in which Snæfellsjökull induces hypnosis in a small community, leading them to believe that they could bring the dead back to life. Another legend tells of a half-troll whose daughter was pushed onto a passing iceberg by her cousin. The half-troll then murdered his nephew to avenge his lost daughter, unaware that she had drifted to safety in Greenland, before he retreated inside the mountain, where he hides broken-hearted to this day. Silhouetted against the night sky, it seems that this strange mountain has always fiercely guarded its secrets. I will just have to find a different way of getting inside.

'Little did I realise what awaited us on the Snæfells peninsula, where the damage wreaked by impetuous nature had created a frightening chaos... though the volcanoes were extinct, the debris that remained bore witness to their former violence.' - Journey to the Centre of the Earth by Jules Verne

Maybe this is your passage to the centre of the Earth, maybe it isn't,' says Guðbjörg Gunnarsdóttir, the park ranger, pointing into a gloomy cave. 'It's not somewhere I'd want to go on my own anyway.'

We are in the lava fields, the strangest and saddest parts of the Icelandic landscape. In Drangahraun, the fury of Snæfellsjökull is recorded in stone - it feels as if every tide of molten rock had frozen still barely a moment ago. Black basalt steeples watch over sheep tracks, a labyrinth of alleyways that pick their way between convulsing rock formations, scorched earth where there were once green meadows.

'We tell children that this is where the elves live, so they keep away,' says Guðbjörg gesturing over the field. It takes little imagination to spot strange figures in the distance - clumps of rock scattered across the land by eruptions - but Guðbjörg is serious. 'People laugh at Icelanders' belief in elves and trolls, but it's not so simple. It's like radio waves - you know they're there, even though you've never seen them.'

Even without elves, there's more to the lava field than meets the eye. Buried under the rock are hidden caverns where, it is said, outlaws banished from Icelandic society took shelter hundreds of years ago. To the east at Hraunfossar, underground streams flow beneath lava fields. The cave beneath us is a dried-up watering hole for cows on the slopes of Snæfellsjökull, only recently emptied of tonnes of mud and snow to reveal a gaping tunnel beneath.

We descend into the Earth. Shining a torch into the gloom reveals boulders swept away in the lava flow, and shelves of rock running downhill and out of sight. The sunlight fades, and our footsteps echo. Verne's world of yawning crevices and subterranean monsters seems close by.

We go further, before Guðbjörg points to a second, deeper chamber, reached only by a rope. The dripping of water resonates around the cave, and I'm reminded of Axel's words in Journey to the Centre of the Earth: 'I had not yet peered into the fathomless pit into which I was about to venture. A rush of vertigo overcame me, and dizziness rushed to my head like wine. Nothing could be more intoxicating than the lure of the void.'

It's possible there are other tunnels yet to be explored, perhaps a whole network running deep beneath Snæfellsjökull and down into the innards of the planet. It's almost tempting to step into the pitch black, snatch a burning torch and begin our own subterranean adventure... but we turn back. After all, who would ever believe that what lies beneath our feet could be any stranger than the landscapes on the surface above?

Oliver Smith is a journalist who was named AITO Young Travel Writer of the Year for his article In Search of Lawrence's Arabia, in the May issue of Lonely Planet Magazine.

The article 'An Icelandic journey to the centre of the earth' was published in partnership with Lonely Planet Magazine.