“Are all your systems functioning?”
“Yes.”
Earthquake? Sandfall? Whatever it had been, Plummet’s descent had stopped now. Visibility was nearly zero. The mist swirled in the lights, thickening and darkening from yellow to brown. Plummet was still vibrating and yawing.
“I’m going back up to three hundred metres. I can’t see a thing. If visibility doesn’t improve, I’ll come all the way up. What’s it like at the surface?”
“Getting worse. The wind’s out of the west at forty knots. We have a hell of a sea running.”
“Any weather reports?”
“You’re about as far as our radios can reach right now. We’re two hundred kilometres off San Francisco and can’t raise anything.”
He started the motor, feeling relieved when its three horsepower kicked in, and reached for the switch that would force compressed air into the ballast tanks.
Without warning. Plummet turned over and nosed down.
Don fell full-length against the low, curved ceiling and slid headfirst into the black-painted forward bulkhead. Something — Plummet or something outside — was rumbling softly. Impossibly, the hull clanged as if struck.
Very slowly, too slowly, the submersible righted itself, and Don fell back onto the couch. What the hell could keep Plummet upside down for that long? Its centre of gravity was too low —
It turned over again. He could feel it start to roll and was braced for it: this time only his feet hit the ceiling, and he kept his grip on the wheel. Loose equipment bounced and clattered around him. Gauges twitched. The interior lights burned serenely on.
“Wait a minute,” Don muttered. The rumble grew louder, so loud he couldn’t hear himself talk. What must have been a fist-sized stone clanged against the hull.
Plummet swayed and righted itself, but began to spin rapidly on its vertical axis. The portholes showed a grey-brown murk. The million-candlepower external floodlights were either torn away or unable to penetrate the mud.
The spin slowed. The rumble was changing, rising in pitch to a rattling hiss. Plummet yawed and pitched. Don groped for the emergency weight-release, but his sight was blurred; his lids felt sticky when he blinked. He wiped his eyes, and his fingers came away smeared with blood. The top of his head hurt; he must have gashed his scalp on one of the gauges.
Before he could reach again for the weight-release, Plummet’s starboard side scraped violently against what must be the canyon wall. The submersible spun completely around and struck the wall again, stopping dead with an impact that flung Don hard into the thin cushion of the couch.
Plummet was lying nose-up at a steep angle. He must have struck a slope on the canyon wall, and now something was holding the craft down. The depth gauge read 450 metres. Stones rattled and banged against the superstructure; the strange, surf-like roar went on. Don caught his breath.
A turbidity current.
It had to be. A quake must have dislodged unstable sediments farther up the canyon. In a frictionless mix with water, millions of tonnes of mud and sand and rock had started to move. Like an avalanche, the current had fed on what it scoured from the canyon floor, increasing in force and speed. He was the first person ever to witness one, but their effects were well known: they could snap undersea cables like threads and carried enormous masses of sediment far out onto the ocean floor. If he hadn’t struck the canyon wall, the current might have swept him onto the abyssal plain, into depths far greater than Plummet could endure.
“Lucky,” he muttered. He would be buried alive instead of being crushed. Rocks were beginning to pile up the superstructure and along the sides of the craft; he could see a couple through one of the portholes.
Yanking the weight-release did nothing. Either the switch was broken, or the eighty-kilogram steel plate had released without any effect at all. Plummet no longer shook as violently under the barrage of stones: they were piling up fast.
Don pressed his fingers against his ears, trying to muffle the noise. He was angry at himself for being frightened, for letting fear slow his thoughts. Blood trickled stickily over his hands from the cut on his scalp. He shuddered, closed his eyes, and opened them again. Maybe he could push the sub away from the canyon wall before the rocks built up and buried him for good.
He grasped the manipulator control and pushed the arm forward. It responded, grating against stone, and Plummet shifted a little. If the ballast tanks were still intact, and the emergency weight came free, Plummet might manage to ascend out of the current.
Cautiously, Don pressed the switch that fed compressed air into the ballast tanks. He was trembling uncontrollably, frightened and excited at once. Taking a deep breath, he pushed the manipulator arm hard against the wall and heard rock scrape against the nose. He pulled the arm back and pushed again. The stern lifted slightly, and rocks thumped down the length of the superstructure.
Don pulled back again, and threw himself forward as he pushed the arm against the wall.
He felt the unmistakable shudder of the emergency weight coming off. Plummet heaved towards the horizontal, banged its nose against the sloping canyon wall, and spun out into the current.
He watched the depth gauge: 410 metres. 408. He was rising slowly through the current. The brown swirl was as dense as ever, with only momentary thinning. Plummet’s rotation slowed.
At 320 metres, the water cleared a little. At 300 metres, the submersible began to ascend more steeply. The water was a chalky-coloured mist; the rumble of the current was still loud, but now came distinctly from below. At 280 metres, Plummet shuddered through the turbulence of the shear zone between the current and calmer water.
Don was still shivering, enough to make it hard to unscrew the cap on his canteen. Wetting a cloth, he wiped blood from his face and hands. His watch cap was stained red. The hair above his left temple was sticky and matted, but he seemed to have stopped bleeding. He rested his forehead on his crossed arms. He could think only in disjointed images: walking along a Vancouver street as a little boy, holding his father’s hand; struggling to the surface after falling into the deep end of a swimming pool; Kirstie’s blue eyes reflecting the Mediterranean sky. He felt sad, somehow, and unaccountably lonely.
Twenty minutes later, Plummet neared the surface. The storm was raising big waves, but fifteen metres below them the sea was calm. Don turned on the VHF and raised Ultramarine at once. Owen Ussery, the ship’s chief scientist, answered.
“You’re okay?”
“A little banged up, but yes, I’m okay.”
“You gave us one hell of a scare, Don. We clocked you at twenty-three knots before we lost you. Do you realize you must have been caught in a turbidity current?”
“Yes! It sure gave me a ride. I was almost too excited to be scared. There must have been an earthquake offshore.”
“No, it was a tsunami, Don. We finally raised San Francisco a few minutes ago. Apparently there was a hell of an earthquake or eruption or both, down in the Antarctic yesterday. Hilo issued a tsunami warning last night, but it’s taken hours to get the word out. The waves got here before the message did.”