Bony was no deep-sea diver; still less was he a bold explorer. As he took that first, possibly fatal step, he paused and looked down.
The base of Airlock Number Two sat about three meters from the bulbous rounded end of the Mood Indigo. That base was where the drive unit was housed, and as the heaviest part of the ship it had hit the sea-bed first when the vessel drifted down through the water. Bony could see, directly beneath him, a broken array of sharp-pointed gold-and-green shafts, two meters long and scattered like toothpicks by the impact.
He held the side of the hatch and lowered himself slowly through the opening. When he was in water up to his waist, he hesitated. He had stated, very confidently, that the chemical properties of deuterium oxide were the same as those of ordinary water. But was that true? Was heavy water just like regular water for all normal purposes, except for its greater density? Bony thought so, but he was no more a trained chemist than he was a trained engineer. Also, he could not tell how strong those pike-like stems beneath him were. He had to be sure that he didn't impale himself on one that still stood upright.
"Are you all right?" said Liddy's voice in his helmet.
"Yes. Just being cautious." Bony had another thought. "I've realized something: radio signals designed for space or air use won't travel through water. Once I'm immersed we won't be able to talk to each other. Don't worry, though, I'll be all right."
I hope. Bony lowered himself farther. Mid-chest. Shoulders. Chin-level, nose-level, eye-level. He was fully immersed, staring into limpid depths. Was this what the oceans on Earth or Europa looked like? He had never been totally under water before, so he had nothing with which to compare. The water had a bluer tinge than he had expected. All the old talk about "the deep blue sea," and it really was. After hanging for a few seconds, he released his hold on the side of the hatch.
He was ready for a sudden drop. Instead, nothing seemed to happen. Another disturbing thought crept into Bony's head. Heavy water was quite a bit denser—eleven percent denser—than ordinary water. Suppose that he, in his suit, was lighter than the salty heavy water that he displaced? Then instead of falling to the sea-bed he would rise toward the surface. He did not know if he could use his suit's thrustors under water. If he went up, he might have no way to return to the ship.
And then he realized that he was in fact drifting downward, so slowly that he had time to tap on the lowest port of the Mood Indigo when he reached it, and still be there to wave reassuringly to Liddy when she hurried over to look out. She mouthed at him, he was not sure what. "Be careful," that seemed clear enough. But the rest of it? "Don't something-or-other."
Whatever it was, he would try not to. Bony turned his attention downward. He was just a meter above the surface, and there was no way that he could avoid landing on the flattened pikes. He was lucky to be so close to the ship, because a couple of meters farther out the thicket of spears still jutted upright.
The final impact was feather-soft. Even so, as his boots touched the spikes they crumbled to a cloud of dust that rose up all around him. They seemed like crystals, infinitely delicate and fragile. Bony realized that he had never been in a moment's danger.
Danger from the spears, that is. Bony stared along the gentle slope of the sea-bed, and as he did so the light around him dimmed. Just as quickly, it brightened back to its earlier level. Bony looked up. Far above him he saw a vague tri-lobed outline, moving away. Something huge, in the water or above its surface, had passed over his head.
Bony shivered. The smart thing to do was to return at once to the Mood Indigo. He had made his point. He had proved that they could leave the ship and make necessary modifications to the auxiliary drive, enough to allow them to leave Limbo's ocean floor. But Bony could see better now, as the dust from shattered pikes settled in the still water. The ship had landed in the lowest part of what seemed to be an underwater valley, right where the standing spears grew thickest. Forty meters away, the world of the seabed faded and merged into a sea of uniform green; but just before that, the array of spears ended. Bony could make out the faint outline of rounder shapes on the slope.
He stood still and checked the condition of his suit. He had air enough for eight hours, ample drinking water if he needed it, and good thermal balance. He felt neither too hot nor too cold. The light around him seemed a fraction brighter than when he first emerged. Assuming that they were on the sea-bed of a planet somewhere in the Geyser Swirl; that the planet rotated on its axis with a period to give it a day comparable in length with an Earth day; and that the planet moved in orbit around a star—lots of assumptions, but each of them reasonable—then the brighter light indicated that it was still morning on Limbo. The only thing at all abnormal was the tendency of his faceplate to become covered with small bubbles. That must be a side effect of the super-aerated sea, and it ought to decrease as the suit visor became the same temperature as the water. Bony could go quite a bit farther, without a danger of being caught by darkness. And if he went back now, Liddy would wonder why.
He moved carefully forward, passing across the broken shafts until he came to the array of upright ones. Each standing spear was a couple of centimeters across and rose taller than his head. Close up, he could see a brighter line running up the middle of each. He reached out to take one between finger and thumb, and at once it shattered. He tried again, with the same result. No matter how delicate his touch, the shafts fell in two. As they broke he heard a faint chime like a crystal bell, and the bright line faded within seconds.
If he wished to know what lay farther up the side of the drowned valley, he had to cross the field of spears. Feeling like a ruffian, too ham-handed to touch anything on this planet, Bony pushed his way through. He left behind him an avenue of destruction. If everything on Limbo was like this, the planet should be off limits to humans. It was far too delicate to withstand human contact.
At the edge of the field of spears, Bony halted and turned to look back at the Mood Indigo. The ship had faded to an outline of dark gray. Its dumbbell shape, the rounded bulbous lower part of drive and cargo hold topped by the slightly smaller ovoid of crew quarters, had an oddly out-of-place quality. Here on Limbo it was the Terran vessel, and Bony himself, who were the aliens.
He waved, wondering if Liddy would be able to see him from so far away. He fixed in his mind the contours of the underwater valley, so that even when the ship was out of sight he would have no trouble returning to it. Finally, he turned and began the slow, buoyant walk that would take him up the slope and onto the undersea ridge that marked the end of the valley.
He was almost floating, but in order to make forward progress up the steep incline he still had to put his feet down and exert pressure on the sea-bed. A carpet of spheres of dull orange-red had replaced the standing pikes, and he could not avoid treading on some of them. They flattened, even under his sea-supported weight of what could not be more than a few pounds; but at least they did not shatter and crumble to dust. Instead they produced an odd wheezing sound, like a chesty old man's sigh of complaint. When he had passed by, they slowly and silently resumed their original shapes.
Life forms? Bony was not sure, but his guess was yes. Experience throughout the Stellar Group showed that life popped up everywhere you thought it possibly could, and in a lot of places where you felt sure that it couldn't possibly. There was life in the sulfur volcanoes of Io, life in the ammonia clouds of Uranus, life on fifty-kilometer fragments of radioactive ice in the far reaches of the Oort Cloud, even viral life of a sort coating arid rock shards of the Dry Tortugas. And this was all within the limits of the extended solar system. When you included the domain of the whole Stellar Group, the variety of life-forms, life-tolerances, and life-locations seemed endless. The idea of life on Limbo seemed very reasonable.
Intelligent life on this planet was another matter. Bony was ready to bet high odds against it. Thousands of worlds lay within the two-hundred lightyear sphere bounded by the Perimeter, and they had so far produced only four intelligent species: humans, Pipe-Rillas, Tinker Composites, and Angels. There was a debatable fifth form on the far-off planet Travancore, in the form of a giant caterpillar-like creature known as a Coromar. The Coromar was capable of speech, which would normally argue for intelligence; unfortunately its entire vocabulary and interests were confined to finding food and eating it. Bony was as fond of his food as the next man—probably a good deal fonder than the next man—but as far as he was concerned the Coromar failed to make the cut.
And then there were dangerous life forms. To be dangerous, life did not have to be smart. It merely had to be hungry, poisonous, bad-tempered, territorial, frightened, or accidentally lethal. Bony, as an Earth form, was almost certainly useless as food for any indigenous form on Limbo or any other alien planet. Unfortunately, that was the sort of discovery a creature made only after an attempt at eating had begun.
Occupied by such disturbing thoughts, Bony came to the top of the ridge. He guessed that he had walked maybe two or three hundred meters and risen twenty meters above the ship's location at the bottom of the valley. Everything was noticeably brighter. He raised his head and stared straight up, wondering how far he was from the surface. When they first arrived, he had guessed at maybe a sixty-meter depth for the Mood Indigo based upon the pressure outside the ship. But that estimate, he now realized, had ignored the air pressure of the atmosphere above the surface of the water. He might be within ten or fifteen meters of air—whatever air on Limbo might be. It must have a high oxygen content, because the waters of Limbo literally fizzed with dissolved oxygen.
The far side of the ridge descended in a shallower slope that seemed to lead to another valley. The sea-bed structures changed again. Now they formed clumps of long green strands with thick purple fingers at the end of each. Bony decided that he had come far enough for one day. He would, if the ship was still here tomorrow, take a closer look then. He was all ready to turn and head back when he noticed something about the green clumps. Although their height and degree of growth varied so that they covered almost the whole sea-bed apparently at random, the positions of their centers were not at all haphazard. They lay along a precise triangular grid, each one about half a meter from its three nearest neighbors.
It could happen naturally. For all that Bony knew, the separation was governed by some precise biological demand for light or nutrients. If, on the other hand, it was not natural, but a farm . . .
Bony sank down on his haunches to examine the nearest clump of plants. He reached out and tugged at one of the purple fingers. It came away easily and split open like a ripe pod, revealing a group of pea-sized objects within. A puff of gas came at the same time, bubbling up into the water. He lifted the pod to the visor of his suit helmet for a closer view of the dimpled seeds. They looked like a food crop, ripely edible—though not probably to humans. One of those might be enough to kill Bony. As he peered at the cluster his peripheral vision caught a movement far away.
They were on the floor of the valley, close to the limit of visibility. Three of them. At that distance, in the diffuse watery gloom, he had no way of judging size. Each one was rounded and iridescent, like an object blown from a collection of different-sized soap bubbles or a figure made by children from balloons, come to life and in its movements oddly ominous. Bony saw—or imagined—a round bubble head supporting bubble eyes that nodded on long thin stalks; a spherical multi-colored body; string-of-bubble limbs or tentacles, that carried the creatures across the sea-bed as though they were floating ghosts.
Carried them this way. By accident, or by intention? Bony did not care to find out which. He had enjoyed as much novelty as he could stand, and his stomach felt knotted with tension. He stooped, to provide as small a visible target as possible, turned, and started back toward the Mood Indigo. He told himself that there were multiple good reasons for going back. Liddy would be worrying about him. He wanted to see her. He was hungry and thirsty. His bladder was uncomfortably full, and although the suit would accommodate such things he preferred the ship's facilities. Even the uncertain pleasures of Friday Indigo's company seemed desirable, compared with that of the creatures—Limbo-ers? Limbics—slithering toward him across the alien corn of the underwater valley.
Only one thing preserved the dignity of Bony's retreat: it was physically impossible to run underwater.
As soon as the ship came into sight he turned to look back. He was glad to find that he left no tell-tale track of suspended sea-bed mud, nor could he see any sign of the bubble creatures.
Even so, the relief when he reached the protective bulk of the Mood Indigo and stood once more below the open airlock was considerable. He didn't feel hungry any more, and the urge to pee had mysteriously vanished. He crouched, leaped, and was able to grab the edge of the hatch on the first try. His head came above the surface of the water, and with another upward heave he was sprawled on the bottom of the lock. He stood up and splashed through knee-deep water to the port on the inner hatch. As he had hoped, Liddy was there. He gave her a thumbs-up and started the process of pumping air that would clear the lock of water. The air pressure in the lock was only thirty percent higher than inside the ship, and the water level dropped as he watched.
He removed his helmet as the outer hatch closed. By the time that Liddy matched air pressures and opened the inner hatch he had his suit halfway off. She interfered with that by coming up behind and giving him a hug.
"I wondered where you'd gone. You disappeared completely."
"I thought that since I was outside and the suit worked fine, I'd take a little look around." Bony tried to be casual. "Where is Friday Indigo?"
"Sleeping, I guess. I haven't heard a sound from up there."
"Still? But he's been asleep for—" Bony saw the clock. "That can't be right. I was gone for hours."
"Thirty-seven minutes, from the time you dropped out of the hatch to the time I saw you coming back. What did you find?"
"Lots of things." Before Bony could say more, a voice from overhead grumbled, "You sure make a hell of a lot of noise down there. Have we sprung a leak or something? I heard a pump."
Friday Indigo came down the ladder. His dark hair was a tousled mess, but he seemed in a surprisingly good mood.
"An air pump," Bony said. "I've been outside, and when I came back in I had to pump water out of the lock. Captain, I think we ought to try to make drive modifications, raise the ship off the bottom, and get out of here as soon as possible."
"What's the hurry all of a sudden?" Indigo wandered into the galley and came out carrying a can of juice. He gulped from it noisily. "We have air, we have food, and the ship isn't about to cave in. I didn't come all this way so we could turn right around and leave."
Bony wondered if it was bravery or stupidity. Did Indigo have any idea of their situation? "I see several reasons to leave, sir. First, we have no idea where we are. As I understand the Link Network, it is impossible to make a link to a place where matter is present. Even a link into air requires special procedures. But we arrived in water."
"All that proves is that you don't understand the Link Network. Nor do I, and nor I suspect does anyone else. But I'm not in a sweat because of it. What else?"
"We've landed in a place like none I've ever heard of. The sea here isn't ordinary water, it's deuterium oxide—heavy water."
Friday Indigo said to Liddy, "Remember I told him it was water?" And then to Bony, "So it's heavy water. I've heard of that. How dangerous is it?"
"Not dangerous at all. I think. But it's—well, unnatural for an ocean to be heavy water. In Earth's oceans, heavy water is only one part in six thousand."
"Precisely why we came. For strangeness." Indigo tossed the empty can into a trash-squeeze and rubbed his hands together. "This is terrific. We've found a whole new world, one nobody has explored before. That information alone is enough to make this expedition famous. And when we get some idea of what sort of things might be here . . ."
"I already have some idea, sir." Bony gestured toward a port. "Things I discovered when I was outside the ship."
Friday Indigo stared at him. "You sound afraid. You're not scared, are you?"
"No, sir." But Bony had been.
"You don't have to be frightened, you know. Not with Friday Indigo as your pilot."
"Yes, sir. Of course." Bony knew that Liddy's eyes were on him, and he felt like a spineless groveler. He and Liddy had agreed that a ship with Indigo flying it was worse than a ship with no pilot at all. "Let me tell you what I saw, sir."
He summarized his findings while he had been outside. When it was told, rather than experienced with elevated pulse rate and nervous stomach, everything sounded flat and unremarkable. When he came to his description of the bubble shapes, Friday Indigo went over to the port.
"Where?"
Bony came to his side and looked at the peaceful forest of green-gold pikes, with beyond them a seascape fading into blue-green haze.
"You can't see them from here. They were over on the other side of that ridge."
"Are you sure you didn't imagine them?"
"Quite positive." But he could see that even Liddy was a little skeptical. "They were there."
"Good. Then tomorrow we'll go and take a look at them."
Bony had to swallow before he could speak. "Our weapons won't work underwater. Suppose that they're dangerous?"
"We'll be in suits. That should be protection against anything like teeth or poison. Your bubble-men won't have anything more than that." Indigo saw Bony's mouth twitch. "They won't, man. Use your brain. If you're worried about lasers or explosives or projectile weapons, forget it. These are sea-creatures. It's a well-known fact that creatures who develop in water, even if they are intelligent creatures, will never discover fire and never be able to develop technology."
Bony wanted to say, "It's not a well-known fact, it's a well-known theory." But it wasn't worth getting into an argument. Even though Indigo was wrong, the captain would ride right over him. Instead Bony said, "Don't you think it's less important to learn about the bubble-creatures than to get the Mood Indigo working again?"
"How? You were the one who insisted that the fusion drive could never operate underwater."
"It won't. But what reason do we have for thinking that Limbo—"
"That what?"
"Limbo. This planet. It's the way I've been thinking of the place. We entered a link entry point back in our solar system, and now we're in the middle of nowhere. In limbo."
"Nonsense. We know that we're in the Geyser Swirl. If only we could get a look at the stars . . ."
"That's my point, sir. We're in water at the moment, but we have no reason to think that the whole of Limbo is ocean. There could be land just a few kilometers away. If we could move the Mood Indigo onto land, we could see the stars and we could use the fusion drive to get off the planet."
"Are you suggesting that we ask your froth-men the way to the nearest land?"
"No, sir!" Bony wanted nothing to do with those floating assemblies of bubbles. "I noticed that when I was outside and high on the underwater slope, the light seemed a lot brighter. It makes me think we're not perhaps all that deep, maybe as little as thirty meters. The buoyancy of the heavy water is greater than ordinary water, because of its greater density. We might be able to float the ship to the surface more easily than we think."
"Not a bad idea." Indigo smiled at Bony. "Good work, Rombelle. Of course, before we do anything with the ship we have to be sure what we'll find up at the surface. Are you volunteering to go out again and take a look?"
Bony was proposing no such thing. He had seen enough of deep-sea diving in modified space suits for one day.
Before he could reply, Liddy said, "Let me do it. I'm no use fixing things inside the ship, but I'm sure I can put on a suit as well as anyone and go up to the surface."
"Do it soon," Indigo said, "before we have to worry about it getting dark." And, as Bony tried to hide his surprise, "Did you think I was doing nothing, while you two were playing your games with airlocks and romping around outside? I adapted one of our light-meters and I've been monitoring the ambient light level for the ship since the time we arrived. This planet has a twenty-nine hour day, and we're more than halfway through the cycle. That means we have maybe five more hours before darkness."
"I'll get ready right now," said Liddy. Bony was still staring at Friday Indigo. He had written the man off completely, and now here came common-sense and a talent for improvisation. Maybe you didn't have to be an idiot just because you were rich.
Indigo was nodding at Liddy. "Carry on, as soon as you're ready. Be sure to carry extra weights and inflate your suit extra hard when you go up. That way, when you bleed away the excess air you'll sink straight back down to the ship. The trip up to the surface will be useful even if you can't see land. We can go again after it gets dark and try for a fix on the stars. That will answer one other important question: where are we in the Geyser Swirl."
More sound sense from Friday Indigo. But Bony recalled the shape that had flown over him as he stood on the sea-bed, a form like a great three-leaf clover. Was that at the surface, or above it? He found himself saying, against his better judgment, "There may be other things up there. Don't you think I should go with Liddy, as a back-up if things go wrong? And shouldn't we take a line with us, so that we can pull ourselves back if we get into trouble? And if we attach an insulated wire, we can have continuous two-way communication with the ship even though the radios don't work in water."
Indigo laughed, "My God, that's four ideas from you in one day. You're less of a fool than you look."
A dubious compliment, at best. But Indigo was continuing, "Now here's an idea for you. You said you intended to see if the suit control thrustors would still work under water, but you didn't do it when you were outside. So why don't you try it now? You can cruise around a bit on the way up or on the way down. Maybe you'll see your mysterious froth-men, and find out what they are up to."
It was phrased as a cheerful invitation, but Bony was under no illusions. He had to go outside again and face the horrible bubble creatures.
He turned to Liddy. "I'll come and help you to operate the airlock. Just give me a half a minute, then I'll be with you."
Bony's urge to go to the bathroom had returned. This time he felt sure that it would not vanish by itself.