Two decades later, IDDP-2 is their second attempt. When we arrive, the sound of machinery whirring to life echoes across the otherwise silent landscape. Metal structures glint in the pinkish winter light. High up in the apparatus, a worker manoeuvres the next section of a drill shaft into place and sinks it into the earth.

As with the first IDDP borehole, the team does not expect to hit magma. But then nobody expected to hit magma that time either. Despite the geophysical imaging survey at Krafla suggesting that the drill tip would come nowhere near it, they ended up drilling into magma three times, twice without realising it. Nobody really knows what’s down there until they drill through it, says project manager Ari Stefansson. “It’s getting more and more interesting as we go deeper.”

Stefansson sits in a heated cabin, looking at the latest readings. A screen shows various figures but the key one stands out near the top – the depth of the drill bit. “We are now at 4,090 metres,” he says. Only a few weeks earlier, the hole officially became the deepest in Iceland when it reached a depth of 3,640m. But there's still another kilometre to go, which they hope to achieve by Christmas.