equipment, facing a challenge fraught with as much risk as they had ever faced before. Jack turned and looked into the swirling darkness below them, reducing his headlamp beam so his vision was not dazzled by the reflection of light from particles in the water. He saw the hazy outlines of the tunnel walls ahead, and the blackness beyond. He felt his breathing tighten, felt the apprehension, and then took a deep breath and relaxed as the adrenalin coursed through him. He was in his element, where all his training and ambition had led him, an underwater explorer about to enter the most extraordinary archaeological site ever discovered. Right now, there was no better place in the world to be. Costas turned to him, his visor reflecting an image of Jack like a photograph of an astronaut in space, then gestured down the tunnel. ‘Good to go?’
Jack steeled himself. They were about to dive into a live volcano . He raised his hand, then pointed into the void. ‘Good to go.’
2
Jack stared down into the narrowing void ahead of him, keeping part of his mind on the smudge of light he knew lay some thirty metres behind them at the entrance to the tunnel. It was like a flash imprinted on his retina, and he tried to hold it there as a reminder that they had an escape route. He looked over at Costas, remembering their shared experience in the mineshaft many years before. They had let all their training and experience kick in, working the rescue methodically from the moment he had jammed his tank valve on the timber and his air had cut off. The problem for Jack was the reflection, years later: what if Costas had not been face to face with him at that moment, when he had struck the timber and dropped their only torch, plunging them into darkness?
Jack had worked hard to turn the nagging uncertainty to his advantage, convinced that it made him a better diver, more alert to danger, but always for a few moments before a dive like this one he had to go through a ritual. He shut his eyes tight, thinking about nothing, deliberately slowing his breathing, remaining spread-eagled and neutrally buoyant. After a moment he took a deep breath, opened his eyes and looked at his wrist readout, checking the depth and temperature. He felt a nudge beside him, and heard Costas’ reassuring voice. ‘You done?’
‘All set. You lead, or me?’
‘It’ll have to be you, Jack. I don’t think I could get around you now, with Little Joey hitched to my front. I’ll be about five metres behind.’
‘Roger that. I’m about to begin my descent.’
‘Watch your external temperature gauge. Remember, it should read no more than a hundred and twenty degrees. We have about sixty metres more in the tunnel before we reach the area we passed through five years ago, on the way up to the inner sanctum.’
‘You mean the magma chamber, full of red-hot lava.’
‘At least we won’t have to use our torches.’
A few years before Jack had been in an IMU submersible off the Kilauea volcano in Hawaii, watching lava pour over the seaward cliffs and roll down the underwater slopes in a glowing orange mass until it had congealed. He had found it a disconcerting experience, with all his instincts telling him that the water around the lava should have boiled and vaporized, and he had wanted to reverse the submersible to avoid falling into the vacuum he felt sure would appear above the flow. And now here he was, not in a submersible but in the water himself, about to swim into the same scenario. He flexed his fingers, looking at the bulbous white Kevlar that was the only barrier between himself and whatever fiery mass lay ahead. He glanced at the readout inside his helmet, seeing the green light showing that the small electric motor running the air-conditioner unit inside his suit was functioning. He pressed his intercom. ‘Cross-check internal temperature readings.’
‘Twenty-two degrees Celsius,’ Costas replied.
‘Seems a little hot. Mine’s twenty.’
‘You’re a Viking, remember? I’m Mediterranean. And I’m keeping myself in training for that tropical island you promised.’
Jack glanced down at the clear plastic tube inside his helmet beside his mouth, leading to a freshwater bag inside the rebreather console on his back. ‘Just make sure you keep hydrated,’ he replied. ‘Remember, the more you sweat, the more likely you are to get the bends when we go back up.’
‘My thermostat’s set at twenty-two max. And I have no intention of being a boil-in-the-bag meal for whatever fiery denizen of the deep lives down here.’
Jack glanced one last time at the stone pillar to his left with the golden Atlantis symbol embedded in it, then manually expelled air from his buoyancy compensator before angling down to follow the slope of the tunnel, kicking forcefully with his fins. He could hear the hiss of the automated buoyancy control bleeding air into his suit, maintaining his buoyancy at neutral. The lamps on either side of his helmet illuminated the tunnel ahead to a distance of at least fifteen metres, showing the ragged edges of the lava where the borer had dug through and a trail of debris on the bottom where the conveyor had taken the broken material up the tunnel and out on to the flank of the volcano. Back up the tunnel the lava had mostly been p hoehoe, billowy and ropy shapes where the molten rock had quickly cooled on contact with the water, whereas in the tunnel ahead it looked like Hawaiian ‘a‘ lava, stonier and more clinky, a result of slower cooling that had left it denser and less aerated. Where the borer had cut into the harder lava, Jack could see a spiralling pattern extending down the tunnel, making it seem like a vortex. As he swam on he began to see tiny bubbles rising from the depths ahead of them, swirling up like a twisting veil.
‘That’s boiling-hot carbon dioxide and sulphur dioxide, the volcano off-gassing,’ Costas said from behind him. ‘That’s the stuff that makes it poisonous to be anywhere near an eruption like this topside without breathing gear.’
Costas had swum up close behind him, and Jack saw his form reflected in the edge of his helmet. The glass visor was a flat surface set on a slight curve where it closed against the helmet, using external water pressure to make the strongest possible seal; after almost a decade using the e-suit, Jack had got used to the centimetre or so of distorted vision it created around the periphery of the glass plate. But now, seeing the elongated form of Costas’ helmet, it seemed like an optical illusion, as if the distorted image around his visor rim had become part of the walls of the tunnel beside him. He began to see multiple images as if he were looking into numerous reflecting mirrors, shifting as Costas moved his headlamp and the reflection changed. He closed his eyes, then opened them again, trying to focus on the tunnel ahead. ‘Tell me I’m not hallucinating,’ he said. ‘For a moment I was seeing multiple images of you on the edge of my visor, as if they were spiralling around the tunnel.’
‘It’s called polyapsia,’ Costas replied. ‘Lanowski’s been telling me about it. It’s a common altered- consciousness vision.’
‘You mean a psychedelic trip. That’s the last thing I want down here.’
‘You were just seeing multiple reflections, set against the apparent swirl of the tunnel ahead of us. Your mind was playing tricks on you. Lanowski thinks that’s what prehistoric people were doing in places like this, in caves and tunnels: having altered-consciousness experiences. What you’ve just seen shows how easily they could have done it. And they wouldn’t have been able to rationalize it as we can.’
Jack blinked and stared ahead, seeing the cut marks made by the titanium bit of the boring machine, then shifted his head so the reflection of Costas was no longer visible. ‘It was disconcertingly easy to fall into it.’
‘Look at it this way. You wanted to return to Atlantis, to get inside the prehistoric mind, right? To see what these people were seeing. Well, you’re doing it now. This isn’t exactly a time machine, but it’s a way of getting into their perceptions. Imagine we’re going through a kind of rocky interface like those Stone Age caves, towards the spirit world ahead of us. Being in a tunnel’s a common hallucination during near-death experiences, too.’
‘I was wondering when you were going to say that. From now on, reality rules, okay?’
‘Roger that. Now let’s get on. We’re down to eighty-five metres absolute water depth, and we don’t want to linger at these depths any longer than we have to.’
Jack felt a surge of adrenalin, suddenly excited at what might lie ahead. He checked his computer readout. Sixty-seven degrees external temperature. The slew of bubbles increased to a fizzy mass, his headlamp beams reflecting off them in a confusing maelstrom of light and colour that refracted through the bubbles, creating images that folded and unfolded. There was more width to the tunnel now, and Costas edged up along his left side, just as the tunnel gave way to a wider natural opening. Costas put his hand out into the bubbles, moving it round. ‘They’re
