The last time planes were grounded across Europe was exactly ten years ago. That was when the almost unpronounceable Eyjafjallajokull Icelandic volcano erupted, blanketing the skies in ash clouds and leaving travellers stranded in various parts of the world.
Curiously, Iceland has enjoyed a tourist boom since then, welcoming no fewer than two million foreign visitors last year, up 50 percent from five years ago.
And a few plucky souls among them head for Eyjafjallajokull - with their hiking boots at the ready.
The volcano is just off Iceland’s ring road on the south coast. It is not particularly remote, nor is it that high at 5 465ft. But you need to be reasonably fit to get to experience the other-worldliness of walking on an active volcano - a notorious one which was responsible for cancelling 100 000 flights and costing the global economy $5-billion.
The glacier of Volcano Katla near Vik, Iceland. Picture: AP
As for the risk of another eruption, you shouldn’t be too worried - before 2010, Eyjafjallajokull had last erupted in 1821. And if it does erupt again, there should be plenty of warning: last time around scientists had detected seismic activity on the mountain three months before it blew its top.
It’s possible to walk up to the rocky protrusions on the edge of the crater which mark the top of the volcano, but it requires crossing an ice cap which has deep crevasses in places.
Peer into these chasms and they seem to be bottomless - not for nothing did Jules Verne imagine his Journey To The Centre Of The Earth starting from another Icelandic volcano, Snaefellsjokull, in the extreme west of the country.
People walk on the black sanded beach in Vik, Iceland, near the Volcano Katla. Picture: AP
Because of the crevasses, it is essential to hire a guide, especially if you want to make it to the very top.
There were, in fact, two eruptions in April 2010 and to reach the crater of the second - and lower one - is a simple walk, because it happened close to the Fimmvorduhals hiking trail, which goes up the eastern flank of the mountain, reaching 3 500ft.
This trail starts at the hamlet of Skogar and almost immediately passes the dramatic Skogafoss waterfall. It is a full day’s hike up and back to the top to see the crater, but it is neither steep nor difficult - just hard underfoot. In few places in the world can you get to experience a landscape so recently shaped by a volcanic eruption. From a distance, you can make out the outline of the main crater - a sunken pit of ice.
The glacier on the north side of the mountain collapsed, sending floods of meltwater around the west side of the mountain and nearly washing away the ring road.
People sit on rocks at the black sanded beach in Vik, Iceland, near the Volcano Katla. Picture: AP
The ice cap - or ‘jokull’ in Icelandic - is far from pristine. Much of the mountain remains covered in a deep layer of ash. Parts of it are covered with black mounds about 10 ft or so high.
Try to climb up them and it is like clambering up a pile of loose gravel. But at the heart of these mounds is incredibly hard ice - the heat of the ash seems to have compressed it.
As for the crater, there is no hissing steam - just a depression in the ground covered with thick ash. It certainly doesn’t look capable of causing so much disruption.
But it is incredible to think that this benign-looking spot is, in fact, an exit point for magma thrown up from many miles beneath the Earth’s crust.
Once back off the mountain there are two tempting local attractions. One is the naturally heated Seljavallalaug swimming pool, built deep in a valley at the bottom of Eyjafjallajokull in 1923. It is a bit rough and ready, and had to be cleared of ash after the eruption. I pass on that one - but the Lava Centre at Hvolsvollur is well worth a visit.
It explains the geology of Iceland’s volcanoes, and screens interviews with locals explaining what it is like living in the shadow of a monster which could erupt and bury your house at any time.
One woman holds up photos of the garden she proudly used to maintain - which now lies buried under several metres of lava.
Eyjafjallajokull offers an insight into the extraordinary power of the natural world. It is both sobering and hugely inspiring.