My guide, David, is a search-and-rescue specialist, which makes him a Mission Impossible Ethan Hunt character in Iceland, I'd imagine. He has to rescue people from volcanoes, glaciers and wild oceans. He can ski and rappel and swing down from helicopters on winches to pluck people from danger.
As we lurch across the lava fields, he's full of dramatic rescue stories involving hapless tourists and isolated farmers.
Yet somehow none of this reassures me as I leap across a raging torrent in a glacial tunnel. David seems not like my potential saviour but a madman who has lured me into a nightmare. This isn't a pretty blue glacier, such as I've seen from the decks of cruise ships.
This is a groaning, collapsing glacier, dirty with debris, coughing up boulders the size of cars, and spitting out entire raging waterfalls of grey snow melt. This glacier is immense, brutal and not a little scary.
I'm in southern Iceland, where Solheimajokull Glacier – a tongue of the even more immense Myrdalsjokull Icecap – squats atop the country's most powerful volcano, hidden beneath 800 metres of ice. Every decade or so the volcano erupts below, causing massive flooding. We've parked our four-wheel drive on a field of black lava crunchy as cornflakes, and hiked up through patches of snow and pouring rain to the glacier's edge.
"Iceland isn't the land of ice and fire as you might imagine, more one of ash and muddy water," says David glumly.
Solheimajokull has a certain beauty. The oldest ice is blue. Trapped ash forms swirling patterns, and basalt chips glitter like diamonds. You wouldn't call this a nice glacier, though. It's simply a heart-thumpingly impressive one. It looms from the mist like a great beast, roaring and gurgling. Its flanks are wounded with crevasses and pockmarked with sinkholes in which cauldrons of melt water swirl.
Its surface is white, but its layers grey and occasionally electric blue. Its rivers are as black and bleak as Mordor. You tackle a walk here with crampons, helmet, ice axe, experienced guide and a great deal of adrenaline. The trail is a rudimentary assembly of ropes, ice-cut steps and rickety wooden planks that lead us through natural tunnels into the glacier's belly. Sólheimajökull is a constantly changing environment, so no route is ever the same, and guides check it daily.
We're told not to stray. You can fall down a pothole concealed by a dusting of snow.
A new moulin can open up right above your head and spew forth an entire river filled with debris. David leads us up a narrow crevasse to a window in an ice wall, and when I peer through I feel dizzy with shock. An immense waterfall is thundering through an ice cave barely an arm's length away, and the ice shakes under my feet.
Is it sensible to be here? I really don't know. I'm terrified, though not terrified enough to turn back. We have to stomp our crampons into the ground like three-year-olds having a tantrum before we take each step. I'm not sure what to do with my ice axe. It wobbles around in my hand as my arm flails with horrible excitement, until David warns me I'm about to impale one of my tour companions.
But I can't turn away. I've never seen nature like this, certainly not this close. A glacier is powerful and raw, a huge filthy creature that could crush you like a beetle. Its surface is foggy and unfathomable and wind-whipped with particles of ice-like daggers. Its interior is dark, its menacing crevasses and cliffs and caves lit only by our uncertain miner's lamps.
In the adventure theme park that is Iceland, this is the most thrilling experience of all.
Qantas will fly from Sydney and Melbourne to Reykjavik via Perth and London from June 2022. Fares from $2165. See qantas.com
Guide to Iceland, a collaboration of more than 1000 Icelandic tour operators, offers accommodation bookings, self-drive tours, car rentals, holiday packages and individual tours, including Solheimajokull glacier hikes. Three-hour tour from $US84 a per ($114) including guide and glacier equipment. See guidetoiceland.is
Vaccinated travellers have unrestricted access to Iceland but must present a vaccine certificate and a negative COVID-19 test taken 72 hours before arrival. Children under 18 are exempt. Travellers must also register before arrival. See covid.is
Brian Johnston travelled as a guest of Abercrombie & Kent and Guide to Iceland.