Iceland's teatime on a time bomb

Into the wild Hekla, the country's most active volcano, could be either be a lovely place for a picnic or the last sight you will ever see.

Hekla last blew its top in 2000 over a period of four days. Since 1104 it has erupted at least 18 times.

From the small and delightful Leirubakki guesthouse perched on the edge of the old Merkurhraun lava flow in remote and wild southern Iceland, Hekla looks harmless. It's little more than a snow-dusted 1,500m mound made up of gentle saddles; not a mountain so much as a hill which appears to be temptingly straightforward to climb. One spring morning last May my wife and I gazed on it from the picture windows in Leirubakki's dining room. Through our binoculars we watched it rising gracefully to a small crater at the summit from which a wisp of steam puffed nonchalantly.

Over porridge, eggs and coffee, we mentally mapped our route to the top: over that saddle to the west, traverse the black valley, skirt around a couple of odd-looking holes and then strike for the summit. Easy. Indeed, when people describe Hekla as an easy climb for novice climbers, they often fail to highlight the small matter of instant death should it erupt while you are sitting on it having a flask of tea.

But Hekla is no hill, the owners of Leirubakki warned us. It is one of the most active and potentially explosive volcanoes on the planet. It has claimed many lives, flattened vast areas of woodland, produced one of the largest volumes of lava in the last millennium, is notoriously unpredictable and is well overdue for an eruption. Iceland's seismologists have turned Hekla into a pincushion with sensor poles which monitor every shimmer and shake in the hope of predicting the next big one. Leirubakki has a direct feed from that seismic information into its excellent multimedia in-house museum (the Hekla Centre) so after breakfast you can wander in and check out just how lively the hill feels today. Of course, if you are a true addict of climbing active volcanoes - and for some unfathomable reason I am - then the livelier the better.

Also, and possibly more importantly, the seismologists are hoping to predict whether (as expected) Hekla will not so much blow its top as burst at the seams. Those odd-looking holes on the volcano's flanks are the gaping mouths of lava tubes and craters which connect to a highly active fissure. They are evidence of not-so-distant eruptions which blew out sideways. Still, bona fide volcano addicts do not dwell on morbid things such as being swallowed by a magma-filled fissure; so instead we tied our bootlaces, donned our Icelandic woollen jumpers and headed out.

There is only one straightforward way to climb Hekla - if you can call climbing a mountain that could bring instant death at any moment straightforward - and that's by driving along the rutted and stony F225 (off Route 26) north of the volcano and heading up on foot from there. Here, more than six kilometres from Hekla's summit, we were already well inside what we volcano-climbers rather dramatically call the "dead zone". Even if you had a Ferrari parked here and the straightest stretch of asphalt, you still probably couldn't outrun a big eruption.

The F225 lay ahead of us like a dead, sun-dried snake across a landscape devoid of life. In all directions was a sea of compacted ash, dust and small lava balls dumped by the last eruption in 2000. We bumped along as far as possible in our non-4x4 and parked on the highest piece of ground we could find, to give us a shiny silver landmark to aim for when descending later across this featureless plain. Fuelled with adrenalin, we pressed our faces into an icy wind that made our eyes water and our ears ache, and began the climb.

I was setting foot on my fifth active volcano and the familiar feeling of electrified fear and foreboding was charging through me as we crunched our way across the wide expanse. Under our feet lay vast reserves of tempestuous magma in caverns several kilometres wide and deep, simmering and ever-eager to be released in cataclysmic fashion. Within a couple of hours we were several hundred metres up the lower slopes. We crossed a ridge and paused to drink in the vista. In every direction we could see 30 or 40km, and in that unfamiliar landscape we found no trace of human influence apart from the empty road and our tiny glistening speck of a car.

We pushed on around a spur and saw, right in front of us, a terrifying hole gouged out of the earth: the exit point for some horrific outpouring of volcanic venom during the last eruption. The roof of its mouth was tarnished with a museum's worth of mineral deposits and the wind moaned mournfully around its crusted lips. The scene was straight out of Dune or any number of sci-fi films in which phenomenal and merciless powers lie beneath the surface of an angry planet and where fragile human visitors are always a breath away from annihilation. We were speechless, staring in awe at this frightful memorial, this relic of terrors past. We turned our backs and climbed higher, on all fours now and sometimes employing the knees and feeling the jab of spiky lava through our trousers.

We scrambled over another ridge and our hands touched the first pockets of ice. Some 100m more and we were on a plateau in a monochrome world where white snow challenged black lava for supremacy. From our temporary eyrie, we gazed down on the wide sweep of the old Merkurhraun lava flow and the tiny white dot of the Leirubakki guesthouse. The wind softened and the sun shone and we sat on a boulder and experienced an overwhelming and completely unexpected feeling of peace and fearlessness; a kind of acceptance of fate. Knowing Hekla could take us at any moment had allowed us subconsciously to turn off our normal survival mechanisms. It was one of the most beatific half-hours we can remember.

Our volcano reverie was broken, appropriately, by a mild shudder beneath us as Hekla coughed somewhere deep in its fiery lungs. Suddenly, its main bulk seemed awfully close and the steam plume from the summit crater had increased. We were desperate to get to the top. The only obstacles separating us were a narrow jet-black lava valley and then a final push up the steep sides, but it was those steep sides, where the snow was polished like an ice-rink, that thwarted our attempt on the summit.

What whimsical, unpredictable, mischievous it was that Iceland would prevent us from scaling one of its volcanoes not by burning our boots with scalding magma but with snow. Winter had persisted late this year and Hekla's snow was unwilling to melt. Without crampons and a sturdy rope we called it a day, had a quick snowball fight, took some pictures and used our anoraks as makeshift toboggans. Only one thing to do, we thought: risk coming back to Hekla next year. [e-mail]