Chapter 4 Under the Waterline

The tide topped out at 1347. Omar had marked the window and Juna had watched the water change. For two hours the flood stopped breathing—the current through the drowned streets went slack, the flotsam stopped drifting, and the olive surface lay as flat as poured concrete. It was the stillest she had ever seen the sea. It was the stillest she ever would see it. She suited up on the granite ledge: harbor diver's boots, a cracked mask she'd sealed with tar from the shed roof, the lead belt wrapped around her waist, and her own fins over everything. She carried a coil of the shed's anchor rope, the waterproof flashlight, and Omar's handheld clipped to her shoulder strap. She had no tank. She had no second mask. She had a diver's breath in her lungs and a rock shelf forty feet down, and she had not talked herself out of the dive yet, which she took as a good sign. "The buoy," Omar said. "Do you see it?" The successor buoy lay on its side, its anchor chain dragging the slope of the sea stack, exactly where a heavy surge had bent it. Its mooring chain ran down at an angle toward the rock itself. "I'll follow the chain down," Juna said. "It holds my line." "Current's at null for another hour. After that, the ebb comes in hard, and this whole channel starts moving. You want to be back on the surface before it turns." "I will be." Omar gave her a long look and handed her a second weight—a length of iron bar bent into a U. "If you find anything worth lifting, hook it. Don't swim it. Don't fight the water." She nodded, pulled down her mask, and went in. The first ten feet were tea-brown and empty. The drowned town's sediment hung in the water like fog, so thick she could see her own hands only as pale shapes. At fifteen feet spent insulation ribboned past her face, and a sheet of plywood wheeled overhead, turning slowly in a pocket of current. At twenty feet the bottom began to show: the roof of a submerged cannery shed, its vent pipes trailing, a single crab pot caught on a gutter. She leveled off and swam the compass heading her body had memorized on a hundred practice swims: west-southwest, down the line of the old channel. The seabed tilted beneath her. The murk thinned as she left the sediment of the drowned town behind, and the water went green, then deeper green, then a dim blue that told her she was over the shock edge of the rock. The anchor chain met her halfway down, a thick muscular rope of rusted iron stretching into the gloom. She grabbed a link, turned, and pulled herself hand over hand to the bottom. The chain ended where it had always ended: at the great iron ring set into the blasted shelf of Signal Rock. She hung there, fins moving slowly to hold her place, and looked. The shelf was not as she remembered it. The old survey photographs, the ones hanging in the harbor office, showed a flat, gray table of blasted stone scribbled with gull droppings at low tide. But eight feet below the level of the blast there was a black opening in the rock, as regular as a doorway, cut into the seaward face of the stack. It was maybe six feet tall and four wide, its edges squared and bolted with heavy steel framing all through. A torn mesh panel hung across it, and behind the mesh, in the dark, something glinted. She swam the opening and brought the flashlight up. The chamber was shallow, no deeper than a closet, cut back into the granite in smooth machine arcs. Bolted to its floor sat a steel equipment case the size of a suitcase, marine-yellow, stamped with a faded logo she did not recognize and a serial number she could read: TF-09-04. Its lid stood open, and a bank of circuit boards inside glowed faintly orange—powered, alive, humming at the edge of hearing. A single heavy cable left the case through a watertight gland in the back wall and disappeared into a borehole drilled through the rock. Underneath the cable gland, welded to the case, a second object waited: a gray cylinder the size of a fire extinguisher, bristling with connectors, stenciled with the same serial and the words SENSOR MEMORY — DO NOT SEPARATE. Juna hung in the doorway, breathing around the ache in her chest, willing herself to be calm. The machine did not care about her. It sent its three beats, its SOS, into the water on its schedule, and it was still doing it now—beneath her, she realized, the case emitted a faint ticking rhythm she could feel through the water in her jaw and her fingertips. The timing gear was clicking along at exactly the pace of the signal Omar had charted. She reached in, unclipped the gray cylinder's retaining clamp, and worked it free. It came loose cleanly, with a magnetized socket and a rubber seal—engineered to be removed and replaced, built to be serviced by divers. It was heavy. Too heavy to swim with one-handed. She hooked the iron bar through its mounting lugs, clipped the anchor line to the hook, pointed herself up, and pulled. The ascent was slow. The cylinder dragged at her, wanting to sink, and her lungs burned, and the current had begun a faint, insistent pull toward the channel—the first finger of the ebb. She climbed the anchor rope, hand over hand, past the roof of the cannery shed, past the plywood sheets and the insulation ribbon, into the tea-brown murk, and broke the surface gasping at 1422, three minutes before the slack died. Omar hauled the cylinder up onto the granite ledge with her, and together they dragged it into the tower. The radio inside had picked up her three keyed beats and had begun the second of her sentences before she cut it off. On the ledge, water streaming, lungs heaving, Juna looked at her find and understood that she had looked under the waterline of her own town and found a stranger living there. The cylinder was a data vault. Omar spent an hour on it with the only tool that mattered—patience—and got it open with a hacksaw blade and a flat-head screwdriver. Inside, his hands grew very still. "Juna," he said, and the change in his voice made her turn around. He was holding, in a shockproof tray, not a circuit board but a paper log. A weather-sealed case had sat behind the electronics, and inside the case, a spiral notebook, written in ink, damp at the edges but legible. The top line read: *Tidefall Deep Array — deployment log — Trip 04 — PI: R. Ibarra.* "Array?" Juna said. "Seafloor sensor network." Omar turned pages with enormous care. "Ibarra. I read his papers. Stanford geophysics, spent ten years piezometers on the Cascadia margin. He had a private outfit in the nineties—sold monitoring services to port authorities. This thing on the rock wasn't a signal buoy. It was a relay." "A relay for what?" "Listen." He read aloud, his voice slow and formal, as if the notebook were scripture: "'Array node R-9 reports strain accumulation at 1.8x background. Event window revised. If the main slip goes, the trench will produce a double pulse. The local relay is set to warn automatically. We anchored it where a tsunami survey team would find it—old Signal Rock, high water, under the blast line. If the town knows what a sinking sea does, it knows to look for the light.'" He stopped, and turned to the last page. There was a date. It was five years old. "What's the light?" Juna said. Ibarra's last line answered her before Omar did: *When the array trips, the SOS runs. When the array trips twice, the light returns a countdown. Countdown to the wave that always follows the first.* She looked down at the open cylinder, at the data connectors and the paper log, and out at the flat, sullen sea where the second wave would come. "How does the relay know the array tripped twice?" "It's wired to the trench." Omar pointed at the borehole in his copied schematic. "There's a cable running off Signal Rock into deep water. The relay reads the sensor field directly. When the benthic instruments detect the physical signature of a second mass movement, they send a pulse down the line, and the relay broadcasts it as these long bursts we've been hearing." The radio hissed. "Then the bursts we heard," Juna said, "the seventeen dashes at 0358—" "That was the array reporting a second slip. It's been counting down since. Every hour, the same encoded number, one less than the last." Omar's hands were steady, but his knuckles were white on the notebook. "I thought it was a code, Juna. I was wrong. It's a clock." "How much is left on it?" He looked at her, and for the first time since the wave, the calm engineering face cracked. "I need the tide table to translate it. But if Ibarra's trigger is what I think it is—a second rupture on the same fault—then the countdown isn't hours. It's days in the best case, and not even a day in the worst." Outside, the ebb had turned. The drowned town began, very slowly, to drain toward the open sea, and the machine under Signal Rock ticked on, sending its warning to nobody but the two of them.