Costas followed his gaze, and then turned to look at him. ‘This is the only chance you’ll have to see what’s there. We can’t go away and wait for things to cool down. That lava’s going to destroy everything here, all of the archaeology. Whatever’s inside that entranceway will be lost forever.’
‘What are the odds for a look?’
‘What’s your predicted gas supply?’
Jack glanced at his computer readout. ‘At current consumption and depth, about thirty-five minutes.’
‘Mine’s thirty. That gives us half an hour to get over there, take a look, and then return here and get back to the submersible. There’s no radio link with Seaquest II until we’re out of the tunnel. If we go out now to give them the geological rundown, we’d never get back in. Look at the rate of rise of the lava. That entrance probably won’t be there in half an hour.’
‘Will an extra half an hour make any difference to the speed of the earthquake-response team?’
Costas paused. ‘The Turkish authorities are already on Category A alert, with evacuation plans on full standby. What we’ve got to say will push them to activate, but there’ll have to be top-level government meetings in Ankara. It’s a huge decision to make. Millions of people will be disrupted.’
‘The odds for us?’
Costas swam forward and peered over the edge. ‘There’s a lot of plume activity just where we want to go. And the lava’s rising. But when have the odds ever been in our favour?’
‘What’s your call?’
‘I haven’t had a chance to test Little Joey yet. I couldn’t face Jeremy and say I hadn’t tried.’
Jack stared at the ancient entranceway, the stairs in front of it now lit up in the orange glow of the lava that was lapping the base of the rock. It was now or never. He thought about what Costas had said. Half an hour might make no difference. But that calculation depended on them escaping alive. If they never made it out and nobody knew what they had seen, that activation might never be ordered. Millions of people on standby might become millions of dead and injured and homeless. He might be about to make the most momentous decision of his career. Of his life. He stared at the ancient rock-cut entrance, his vision narrowing to a tunnel again, one that seemed to draw him forward over the burning pit in front of them.
‘Okay,’ he said. ‘Let’s do it, and then let’s get the hell out of here.’
3
J ack swam to the edge of the tunnel and looked at the underwater magma lake, watching the yellow-brown haze that seemed to undulate over the lava as plumes of bubbles rose through it and shimmered towards the ceiling of the cavern in the darkness far above. He knew that to swim from the ledge over the lava would be like walking on quicksand, with the rising bubbles pulling on his buoyancy and the plumes acting like sinkholes in the water. Far out in the middle he watched a spectacular geyser of molten rock arch upwards, its surface speckled with bubbles of gas. He turned back, checking the gauge readout inside his helmet. They were eighty-five metres beneath the surface of the Black Sea, at least twenty-five metres below the outer flank of the volcano, and he was down to the final third of the air mixture in his rebreather. He had twenty-five minutes left at this depth, no more, before going on to his reserve supply. There would be no chance of an emergency ascent from this depth to the surface and Seaquest II; their only option was to stick to plan and return up the tunnel to the submersible. Getting to the ancient entranceway and then coming back here would be cutting it fine.
He turned to Costas, who had reached down and opened a Velcroed Kevlar flap on his left thigh, pulling out a tube about the length of his forearm. One end was attached to a spool of what looked like heavy-duty fishing line. He clipped the spool to a carabiner on the chest strap of his rebreather backpack and then twisted the tube, causing a handle like a pistol grip to fold out below. Another twist further up and a metal rod with a point like a harpoon snapped out of the front. He wrapped his right glove around the grip and put his other hand further up the tube. ‘I haven’t had a chance to show you this yet,’ he said.
‘Odd place to go spearfishing,’ Jack said.
‘It’s something I’ve been playing with since we were here five years ago,’ Costas replied, eyeing the rock face ahead of them. ‘You don’t tend to think that getting through submerged caverns would be an issue because you can swim through them, but thinking about volcanic activity made me wonder what it would be like if some force were dragging us down, exerting a pull on buoyancy exactly like those gas eruptions would do now.’
‘Got you,’ Jack exclaimed. ‘It’s a grapple gun.’
Costas pressed his wrist control panel, and Jack saw a thin shaft of light from his helmet where a laser rangefinder penetrated the gloom. ‘Twenty-six metres to that ledge,’ Costas murmured. ‘The grapple spear has a lead core to increase weight and the shaft is as narrow as possible for minimal water resistance, but even so its effective range is only about twelve metres. It’ll go further but you need good force of impact for the head to explode.’
‘Explode?’
‘The first ten centimetres of the shaft contains a joined matrix of rods made of titanium with a magnetic ferrous core. The head impacts the rock and detonates a small C-5 charge, and the rods shoot into every nook and cranny for ten centimetres or so around the point of impact. Then they’re locked tight by an electromagnetic pulse I fire down the wire from the gun.’
‘And then you reuse it?’ Jack pointed across the canyon. ‘We’re going to need two lengths.’
‘Once it’s wedged into the rock and magnetized, it won’t come out. But there’s a second head below the first on the shaft, and you can detach the line from the fired head and put it on the second. It’s a gamble, Jack. The total distance is several metres beyond the specs.’
‘How do we get back?’
‘That entranceway is about five metres higher than we are here. We’ll have to free-swim back, but if we launch ourselves with maximum buoyancy we could swim in an arc and land back here without being pulled down.’
‘Okay. Let’s get going.’
‘Move behind me. This thing fires a substantial black powder cartridge.’ Costas clicked on his laser rangefinder again and aimed at the jagged crevice he had been eyeing on the wall, then pulled the trigger. There was a violent shudder and a jet of bubbles and the spear shot off from the tube, pulling the line behind it. The spool abruptly stopped reeling and Costas was pulled forward, just holding himself in time from being yanked off the ledge over the rising bubbles. He pulled hard on the line, then looked back at Jack. ‘Okay. It’s held.’
‘What’s the drill?’
‘I stay here, you swim along the line. You get there, I swing off this ledge and follow you.’
Jack leaned over the void. ‘That line’s ten metres long, and the lava’s what, eight metres below us? That puts you in the soup.’
‘That’s where you come in. As I swim out as fast as I can from here, you reel in the slack. That way if I’m pulled down, the line will hold me high enough above the lava.’
‘Roger that,’ Jack said, pushing himself off and grasping the line in front of Costas. ‘You secure?’