Ice-Driller and Study-up settled into the small cabin. It was comfortable space-wise for the diminutive creatures, but cargo took up most of the internal volume. The pressure continued to drop, and their bodies wanted to expand, but slower ascent and counterpressure from their clothing kept them in shape. It would take at least a sleep’s worth of time for the compressed gas bubbles in their bodies to equalize. At the highest depth, through the cracks and shafts in the ice, near Nullworld, the low pressures could permanently deform a decapod ascended quickly. Still, it would be sixty kilolengths to the ice wall, then another few to the end of their universe. A long time to ascend, nearly sixty thousand standard lengths of their bodies. They talked in low volume to pass the time, but were careful not to raise their sonar signature. They wanted to keep their noise below the ambient sound of an ovoid shape ascending through the water.

“Hungry?” he asked and unpacked two crates using two arms each. The central half of the ascender held cargo crates strapped to the walls of the ascender with rope and held in the centerline for balance. Around each of the four sides, a narrow area existed to swim around.

“Sure, I packed some vent clams in that sack,” she said. She grabbed the sack from him and ripped it open.

The clams still had hard shells, but were boiled directly in a hydrothermal vent, which caused the creature to burst open at the seams. Then it was re-wrapped with a cut portion of a tube-sponge. Ice-Driller ripped at the flesh with his beak. Small bits of flesh floated around, which he greedily sucked back in. It tasted heavily of salt, minerals, and with a slight smoke flavor.

“So you still believe everything your father teaches?”

“Yes.” Ice-Driller finished his bite. “I don’t see why it is so heretic to think god made more. In the center, there is Fire, and outside that is Rock, enveloped again by Water, and finally Ice. And nothing more. That’s how the story goes, right? God rested on the fifth tide and thus Nullworld was.” Ice-Driller said. “But why is it so hard to believe something or parts of something are out floating in the null—why couldn’t God have made more?”“And I’m as flexible with theology as any modernists.” Study-Up said. “I believe there’s more.”“I was there when he exposed the sonographic plates—I developed them. There is something giant beyond the ice. It has to be more far more massive than God to explain the bulge in the ice. So big it tugs at God measurably.”

Study-Up put down her clam. “But are you sure we—you understand what you’re sensing? What if you’re just conveniently collecting observations that match your ideas? Imagine you’ve set out a net with large holes that captures only one size of fish, and the small ones glide on through. Then claim ‘there’s only large fish,’ is the Academy unreasonable to request more?” she asked.

“Resorting to fishing metaphors now? We’ve known that there are sometimes loud bangs of seismic activity out on the ice. The ancients thought it was Nethros, the god of Death, Nullworld, and Zero, throwing rocks at our God. Where do those rocks come from? I think the Nullworld is a much lighter medium, less than gas, with its own sediments floating. It certainly seems too thin and cold for life.”

“But yet you persist in having us leave the warmth and material of the city’s hot smokers to study the ice.” Study-Up replied.

“Ha, we met under the ice. You left too.” The small parts of his skin that were visible flashed a playful color.

Her skin returned a coy blue. “True, but I wasn’t trying to break the ice. Just study low temperature life; the creatures that thrive on the thinnest of energy. You know, more food and all.”

She sucked in a big siphon of water and shot up the side of the cargo area to the cockpit. “But does it even matter though? Is it of any consequence now?” she asked. “The Center, if you believe God lives there, supplies us with all heat and material. Enough to build a society. Even if another god is bigger, so what? The best way to get people to accept an idea is through their throat. They’ll believe it when they can eat it and it feeds them.”“Maybe you’re right.” Ice-Driller paused. “What has this knowledge produced? Ostracization. Arguing with idiots. Perhaps we should find a quiet place to settle down in another city.”

“And raise—”

Ice-Driller flashed danger blue.

he tapped out the word on a nearby object.

The sounds below—the wake—had changed.

He could hear through the walls of their vessel. Something was under them… Following.

Though the vessel was streamlined, it produced a disturbance in the water; they visualized a change in the static sound beneath.

Faintly… but growing larger.

Study-Up sensed it too now and returned a danger blue pattern on her skin.

Much larger and louder now.

Huge! And it was coming after them.

There was no use stopping and hiding in silence. The ascender was too obvious to evade detection at close range.

“Mandible Shark! Get the toxin.” Ice-Driller yelled.

Study-Up rifled through a small compartment made of ridged shell. Inside were five small darts packaged together. Study-Up grabbed the pack.

Meanwhile, Ice-Driller sent out a small burst of echolocation through the bottom, to get a sight of where the shark was. The visualization returned echoes showed the large articulated jaw which was almost around the vessel.

“Brace—”

Sounds flooded their consciousness. Squeals of tooth on metal. Both could visualize the creature. Its huge gaping maw, used to kill and swallow prey larger than itself. It let out its own burst of sound. Ice-Driller’s head hurt from the intensity and his sonic vision went white. Then the creature shook the craft rapidly back and forth, an instinct to tear flesh. They could hear loose items slapping against the interior wall, but the vessel held solid. Containers loosened, and it threw the riders around. The shark slowed the rate of ascent, then let go a moment, unable to understand the bizarre ‘shell’ of the ascender that was protecting the decapod prey within.

“Here.” Study-Up clutched the dart package tightly and crawled arms over arms to the center.

Ice-Driller had two long hollow poles and screwed them together until it was about twice his length. He had trouble maneuvering it in the tight, disheveled compartment, but his other prehensile tentacles steadied any loose cargo.

With two tentacles he steadied the tube, while Study-Up gave him a single dart.

“We have five.”

They heard the shark bite down on their ascender. The vessel’s walls creaked with the pressure of the shark's jaws, but they built those walls to handle pressure, even striking the ice at high speed.

“Pop,” they heard the shark’s jaws dislocate as it attempted to swallow the vehicle whole. The mandible shark can live many tides in extended torpor while it digests its food. Ice-Driller placed the dart into the receiver in the middle of the tube, then he shot a burst of water from his propulsion siphon cylinder’s top. The dart made a satisfying voomp as it exited the tube. Ice-Driller could hear the whack of impact.

Sounds of thrashing filled their minds and more items were liberated from their containers and dinked against the metal walls. Each decapod used every free tentacle and secured any loose object.

Silence.

The thrashing stopped. They loaded another dart and prepared.

Ice-Driller pinged. All hearts beat quickly. But another spasm didn’t come. Jaws loosened and they could hear loudly the sound of teeth scratching across metal.

That sound died away, and the giant shark sunk away drunkenly, unwilling to pursue.

“Swim away, bone-brain.” Ice-Driller said.

Study-Up stowed the darts back away, while some free tentacles rummaged through the supplies bins. She found what she was looking for, a small bomb. The cylinder contained two chemicals separated by a thin shell. One end contained a small propulsive spring. Once shot away from the user, the spring also pierced a small enzyme bag which dissolves the shell separating potassium and other chemicals from the surrounding water. The chemical reaction would produce a small explosion. Much too small to kill such a massive beast, but enough to deafen it.

“I’ve got the charge,” she said.

They both listened to any other sounds, gently sweeping their sound melon, a mass of fat tissue, left and right trying to visualize mandibled monster.

Ice-Driller opened the small posterior pressure lock and loaded the charge in. He moved over to a cone-shaped protrusion inside of the ascender, which acted as a sound lens. He brought his melon in contact with it and swept the cone around its limited traverse, and then let out a long exhale of water from his siphon.

“I think it’s gone.”

Silence, except for the water. The ascender’s sound profile had changed; bite marks had the hull altering the wake’s sound.

Ice-Driller went to the pilot’s hutch and checked the pressure gauge. “Wait More,” he knocked out in tap-code.

They stayed tense and silent for many more kilo-moments.

Once they were safely inside the bathypelagic zone, Ice-Driller finally spoke. “We’re safe.” And it was true. Nothing dangerous went this high. The nutrients were too sparse—the pickings too slim.

Some creatures existed in this dead zone, but the ecology couldn’t support large predators. Prey were small, and the native predators even smaller, and their distensible jaws and stomachs could not even swallow a pupa decapod. Life here was adapted for passive floating in the water columns, which alternated between updrafts bringing a relatively rich feast, and downdrafts bringing oxygen.