"Well, it's like this-"

"No games, please, and don't try ragging the greenhorn. I am asking out of professional curiosity. I am head safety engineer at Luna City and I am asking what precautions this bathyscaphe can take against possible collision with large creatures."

Javan looked embarrassed. He muttered, "Actually, there have been no incidents."

"Are any expected? Even as a remote possibility?"

"Anything is remotely possible. But actually sperm whales are too intelligent to monkey with us and giant squid are too shy."

"Can they see us?"

"Yes, of course. We're lit up."

"Do you have floodlights?"

"We're already past the large-animal range, but we have them, and I'll turn them on for you."

Through the black of the window there suddenly appeared a snow-storm, an inverted upward-falling snowstorm. The blackness had come alive with stars in three-dimensional array and all moving upward.

Demerest said, "What's that?"

"Just crud. Organic matter. Small creatures. They float, don't move much, and they catch the light. We're going down past them. They seem to be going up in consequence."

Demerest's sense of perspective adjusted itself and he said, "Aren't we dropping too quickly?"

"No, we're not. If we were, I could use the nuclear engines, if I wanted to waste power; or I could drop some ballast. I'll be doing that later, but for now everything is fine. Relax, Mr. Demerest. The snow thins as we dive and we're not likely to see much in the way of spectacular life forms. There are small angler fish and such but they avoid us."

Demerest said, "How many do you take down at a time?"

"I've had as many as four passengers in this gondola, but that's crowded. We can put two bathyscaphes in tandem and carry ten, but that's clumsy. What we really need are trains of gondolas, heavier on the nukes-the nuclear engines-and lighter on the buoyancy. Stuff like that is on the drawing board, they tell me. Of course, they've been telling me that for years."

"There are plans for large-scale expansion of Ocean-Deep, then?"

"Sure, why not? We've got cities on the continental shelves, why not on the deep-sea bottom? The way I look at it, Mr. Demerest, where man can go, he will go and he should go. The Earth is ours to populate and we will populate it. All we need to make the deep sea habitable are completely maneuverable 'scaphes. The buoyancy chambers slow us, weaken us, and complicate the engineering."

"But they also save you, don't they? If everything goes wrong at once, the gasoline you carry will still float you to the surface-. What would do that for you if your nuclear engines go wrong and you had no buoyancy?"

"If it comes to that, you can't expect to eliminate the chances of accident altogether, not even fatal ones."

"I know that very well," said Demerest feelingly.

Javan stiffened. The tone of his voice changed. "Sorry. Didn't mean anything by that. Tough about that accident."

"Yes," said Demerest. Fifteen men and five women had died. One of the individuals listed among the "men " had been fourteen years old. It had been pinned down to human failure. What could a head safety engineer say after that?

"Yes," he said.

A pall dropped between the two men, a pall as thick and as turgid as the pressurized sea water outside. How could one allow for panic and for distraction and for depression all at once? There were the Moon-Blues-stupid name-but they struck men at inconvenient times. It wasn't always noticeable when the Moon-Blues came but it made men torpid and slow to react.

How many times had a meteorite come along and been averted or smothered or successfully absorbed? How many times had a Moonquake done damage and been held in check? How many times had human failure been backed up and compensated for? How many times had accidents not happened?

But you don't payoff on accidents not happening. There were twenty dead-

Javan said (how many long minutes later?), "There are the lights of Ocean-Deep!"

Demerest could not make them out at first. He didn't know where to look. Twice before, luminescent creatures had flicked past the windows at a distance and with the floodlights off again, Demerest had thought them the first sign of Ocean-Deep. Now he saw nothing.

"Down there," said Javan, without pointing. He was busy now, slowing the drop and edging the 'scaphe sideways.

Demerest could hear the distant sighing of the water jets, steam-driven, with the steam formed by the heat of momentary bursts of fusion power.

Demerest thought dimly: Deuterium is their fuel and it's all around them. Water is their exhaust and it's all around them.

Javan was dropping some of his ballast, too, and began a kind of distant chatter. "The ballast used to be steel pellets and they were dropped by electromagnetic controls. Anywhere up to fifty tons of it were used in each trip. Conservationists worried about spreading rusting steel over the ocean floor, so we switched to metal nodules that are dredged up from the continental shelf. We put a thin layer of iron over them so they can still be electromagnetically handled and the ocean bottom gets nothing that wasn't sub-ocean to begin with. Cheaper, too…But when we get out real nuclear 'scaphes, we won't need ballast at all."

Demerest scarcely heard him. Ocean-Deep could be seen now. Javan had turned on the floodlights and far below was the muddy floor of the Puerto Rican Trench. Resting on that floor like a cluster of equally muddy pearls was the spherical conglomerate of Ocean-Deep.

Each unit was a sphere such as the one in which Demerest was now sinking toward contact, but much larger, and as Ocean-Deep expanded-expanded-expanded, new spheres were added.

Demerest thought: They're only five and a half miles from home, not a quarter of a million.

"How are we going to get through?" asked Demerest.

The 'scaphe had made contact. Demerest heard the dull sound of metal against metal but then for minutes there had been nothing more than a kind of occasional scrape as Javan bent over his instruments in rapt concentration.

"Don't worry about that," Javan said at last, in belated answer. "There's no problem. The delay now is only because I have to make sure we fit tightly. There's an electromagnet joint that holds at every point of a perfect circle. When the instruments read correctly, that means we fit over the entrance door."

"Which then opens?"

"It would if there were air on the other side, but there isn't. There's sea water, and that has to be driven out. Then we enter."

Demerest did not miss this point. He had come here on this, the last day of his life, to give that same life meaning and he intended to miss nothing.

He said, "Why the added step? Why not keep the air lock, if that's what it is, a real air lock, and have air in it at an times?"

"They tell me it's a matter of safety," said Javan. "Your specialty. The interface has equal pressure on both sides at all times, except when men are moving across. This door is the weakest point of the whole system, because it opens and closes; it has joints; it has seams. You know what I mean?"

"I do," murmured Demerest. There was a logical flaw here and that meant there was a possible chink through which-but later.

He said, "Why are we waiting now?"

"The lock is being emptied. The water is being forced out."

"By air."

"Hell, no. They can't afford to waste air like that. It would take a thousand atmospheres to empty the chamber of its water, and filling the chamber with air at that density, even temporarily, is more air than they can afford to expend. Steam is what does it."