“It’s odd getting direct sonar input,” said Orphu. “It’s not so much like better hearing, it’s more as if my skin had suddenly enlarged to…”

“There it is,” interrupted Mahnmut. “I see it. The wreck.”

Perspectives and visual horizons were different there, of course, on the so-much-larger Earth than the Mars he’d almost gotten used to, even more out of proportion to perceived distances on the tiny Europa, where he had spent all the other standard years of his existence. But sonar readings, deep radar, mass-detection devices, and his own eyes told Mahnmut that the stern of this wreck was about five hundred meters dead ahead, lying on the silty bottom just a little below The Dark Lady’s depth of seventy meters, and that the crumpled boat itself was around fifty-five meters long.

“Good God,” whispered Mahnmut. “Can you see this on radar and sonar?”

“Yes.”

The wreck lay on its belly, bow-down, but the bow itself was invisible beyond the shimmering forcefield that held back the Atlantic Ocean from the dry strip of land that ran from Europe to North America. What made Mahnmut stare in amazement was the wall of light from the Breach wall itself. Here at more than seventy meters depth, where even in Earth’s sunlit oceans the bottom should be inky black, dappled sunlight illuminated the terminus of water and dappled the moss-green hull of the sunken sub itself.

“I can see what killed it,” said Mahnmut. “Does your radar and sonar pick up that blasted bit of hull above what should be the engine room? Just behind where the hull humps up to the long missile compartment?”

“Yes.”

“I think some sort of depth charge or torpedo or missile exploded there,” said Mahnmut. “See how the hull plates are all bent inward there. It cracked the base of the sail and bent it forward as well.”

“What sail?” asked Orphu. “You mean a sail like the triangular one on the felucca we took west up the Valles Marineris?”

“No. I mean that part that sticks up way forward, almost to the force-field wall there. In the early submarine days, they called it a conning tower. After they began building nuclear subs like this boomer in the Twentieth Century, they started calling the conning tower a sail.”

“Why?” asked Orphu of Io.

“I don’t know why,” said Mahnmut. “Or rather, I have it in my memory banks somewhere, but it’s not important. I don’t want to take the time to do a search.”

“What’s a boomer?”

“A boomer is the early Lost Era humans’ pet name for a ballistic missile submarine like this,” said Mahnmut.

“They gave pet names to machines built for the sole purpose of destroying cities, human lives, and the planet?”

“Yes,” said Mahnmut. “This boomer was probably built a century or two before it was sunk here. Perhaps built by one of the major powers then and sold to a smaller group. Something sank it here long before this groove in the Atlantic Ocean was created.”

“Can we get to the black hole warheads?” asked Orphu.

“Hang on. Let’s find out.”

Mahnmut inched The Dark Lady forward. He wanted nothing to do with the forcefield wall and the empty air beyond it so he never moved closer to that forcefield than the missile compartment of the wreck itself. He had The Dark Lady play powerful searchlights all over the wreck even as his instruments probed the interior of the ancient sub.

“This isn’t right,” he murmured aloud on their private line.

“What’s not right?” asked Orphu.

“The sub is overgrown with anemones and other sea life, the interior is rich with life, but it’s as if the sub sank here a century or so ago, not the two and a half millennia or so it would have to have gone down.”

“Could someone have been sailing it just a century or so ago?” asked Orphu.

“No. Not unless all our observation data has been wrong. The old-style humans have been almost without technology the last two thousand years down here. Even if someone had found this sub and managed to launch it, who would’ve sunk it?”

“The post-humans?”

“I don’t think so,” said Mahnmut. “The posts wouldn’t have used something so crude as a torpedo or depth charge on this thing. And they wouldn’t have left the black hole warheads here ticking away.”

“But the warheads are here,” said Orphu. “I can see the tops of them on the deep-radar return, with the critical-one black hole containment fields inside. We’d better get to work.”

“Wait,” said Mahnmut. He had sent remote vehicles no larger than his hand into the wreck and now the data was flowing back through microthin umbilicals. One of the remotes had tapped into the command and control center’s AI.

Mahnmut and Orphu listened to the last words of the twenty-six crew members as they prepared to launch the ballistic missiles that would destroy their planet.

When the testimonials and data flow were finished, the two moravecs were silent for a long minute.

“Oh, what a world,” whispered Orphu at last, “that hath such people in it.”

“I’m going to come down and get you ready to go EVA,” said Mahnmut, his voice a dull monotone. “We’ll look at this problem from close up.”

“Can we look into the dry area?” asked Orphu. “The gap?”

“I’m not going near it,” said Mahnmut. “The forcefield might destroy us—the Lady’s instruments can’t even decide what the field is made of—and I promise you that this submersible of ours is no good in air and on dry land. We’re not going near the breach.”

“Did you look at the dropship’s aerial photos of the bow of this wreck?” asked Orphu.

“Sure. I’ve got them on the screen in front of me,” said Mahnmut. “Some serious damage to the bow, but that doesn’t concern us. We can get at the missiles back here.”

“No, I meant the other things lying around on the dry ground out there,” said Orphu. “My radar data might not be as good as your optic images, but it almost looks like one of those lumps lying there is a human being.”

Mahnmut peered at his screen. The dropship had shot an extensive series of images before it had flown off and he flicked through all of them. “If it was a human being,” he said, “it’s been dead a long time. It’s flattened, limbs splayed wrong, desiccated. I don’t think it was—I think our minds are just trying to see that shape amidst random stuff. There’s quite a debris field out there.”

“All right,”said Orphu obviously aware of their priorities. “What do I have to do to get ready here?”

“Just stay where you are,” said Mahnmut. “I’m coming down to get you. We’ll go out together.”

The Dark Lady sat on its stubby legs not ten meters west of the stern of the wreck. Orphu had wondered how they would exit through the cargo bay doors set in the belly of the Europan submersible with the ship sitting on the bottom of the ocean, but that question had been settled when Mahnmut had extended the landing legs.

Mahnmut had entered the cargo bay through the interior airlock and tapped into direct comm contact with the big Ionian while the submersible pilot carefully flooded the hold with Earth ocean water, equalized pressures, and then opened the cargo bay door. They’d disconnected Orphu from his various umbilicals and the two had gently dropped to the bottom of the ocean.

As cracked and ancient as Orphu’s carapace was, he didn’t leak. When he showed curiosity at the pressure readings his shell and other body parts were reading, Mahnmut explained.

The atmospheric pressure up above, on a theoretical beach or just above the surface of the ocean here, held relatively steady at 14.7 pounds per square inch. About every 10 meters—actually every 33 feet, Mahnmut said, using the old Lost Era measurements with which Orphu was equally comfortable—that pressure increased by one atmosphere. Thus at 33 feet of depth, every square inch of the moravecs’ outer integument would feel 29.4 pounds of pressure. At 66 feet, they would be under three atmospheres, and so forth. At the depth of this wreck—more than 230 feet—the sea pressure was exerting eight atmospheres on every square inch of The Dark Lady’s hull and the moravecs’ bodies.