Just after 11am, with dawn only just beginning to inch over nearby crags, we get the signal from Fridrik to assemble.
Wearing helmets and armed with torches, we follow obediently in single file as we trudge through crisp snow towards a small opening in the vast lunar landscape. The mercury hovers around zero, although the bracing wind chill has no trouble convincing my face that it's more like -8C.
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Recent snowfall makes cutting makeshift steps down into the hole - usually wider and more accessible - a necessity. While Fridrik chips away, the rest of our party watch him labour. The apprehension is palpable. "When you go down, mind your face on the rock," says Orn, his colleague and fellow geologist from Extreme Iceland, flashing a wry come-hither smile. In the absence of volunteers, I step forward. With little more than a boot on the improvised icy stairs, I slip on my backside and before I know it am careening after Fridrik down into the darkness and the centre of the earth.
Leidarendi, ominously translated as "end of the road", is a volcanic cave system less than 20 minutes drive from the centre of Reykjavik, the world's northernmost capital. The city stands on what would have been bubbling tides of lava and the scene of ferocious volcano eruptions.
I have a point to prove after my entrance to the cave, scrambling over ice and wax-like rock formations or planking under low ceilings and stalactites. In the torchlight, we catch sight of a sizeable crack above us; the scars of millennia of recurring earthquakes.
Reykjavik sits on some of the newest land in the world. In fact, Iceland marks the volatile divide between the North American and Eurasian tectonic plates which shifts up to 4cm a year. It's a land in constant regeneration thanks to volcanic and earthquake activity and Reykjavik is just miles from the action.
"Icelanders are tough. We have to be," explains Fridrik. We take some comfort from his membership of the ICE-SAR, Iceland's elite volunteer search and rescue organisation. Nearly 6% of the population have been trained to answer emergency calls in commonly inclement weather and during potential natural disasters.
Maybe that's where their devil-may-care outlook stems from. They're hardy, yes, but Icelanders are party animals too. The volunteers fund their vital efforts by selling fireworks to the public, which goes a long way in explaining Reykjavik's pyromaniac New Year's Eve celebrations.
From our 360-degree vantage point at the Perlan, one of the highest points in the city, we see nothing but flashes, explosions, streaks and bangs as far as the eye can see. It's the same throughout Iceland, we're told. There's no restraint until the bells either. Fireworks pop from homes and pavements from 9pm and grow in frequency until midnight, when there's a crescendo of noise and light so intense the snow-marbled mountains on the north side of Faxa Bay, until now obscured in total darkness, are lit up. Once the fireworks run dry, celebrations move to the city's bars and clubs.
One-third of Iceland's 300,000-strong population lives in or around the capital. Despite its size and quaint multicoloured matchbox houses, Reykjavik is a liberal city with a vibrant cultural scene and raucous nightlife. Locals head out late to hotspots that trade well into the wee small hours.
It's telling that when poring over lunch menus, a special Hangover Killer is the first option to catch your attention: two courses of comfort food, a "hangover" sandwich and a milkshake made with Jack Daniels capped off with a side of painkillers.
If that doesn't cure you, the powder-blue waters of Reykjavik's hot springs will. There are seven public thermal pools dotted around the city but perhaps the largest and best known is the Blue Lagoon on the Reykjanes peninsula. The spa's geothermic seawater is a sure-fire way to kick-start my new year aspirations. Obscured by billows of steam and mounds of basalt, the short-lived winter sun hangs low in the sky when we arrive for a pick-me-up before our flight.
I leave my masculinity on the decked lagoon-side with my bathrobe and lather up my face with a volcanic scrub in the balmy water. With one hand I feel frost forming in my wet hair while the other nurses a beer from the submerged bar. It would be all too easy for your mind to drift and forget where you are, except for the unmistakeable pique of sulphur on the air that can only mean you're in Iceland.
EasyJet (easyjet.com) has return flights from Edinburgh to Reykjavik from £80.88.
WHERE TO STAY
David Walsh stayed at Víibrekka 21, a four-bed self-catering cabin a short drive from Reykjavik priced at $350 (£211) per night based on a minimum three-night stay or $1750 (£1056) for a week. Visit homeaway.co.uk/p990623.
WHAT TO DO
The volcanic veins caving tour by Extreme Island (extremeiceland.is) costs 9000 ISK (£47). For Blue Lagoon packages visit bluelagoon.com.