"If you look out on the right," said the tour guide - a young Woods Hole graduate, making a little money in his vacation - "you'll see the 'down' cable, stretching up to Explorer . And there's a module on the way right now, with its counterweight. Looks like a two-ton unit - "And there's a robot going to meet it - now the module's unhooked - you see it's got neutral buoyancy, so it can be moved around easily.

The robot will carry it over to its attachment point on the lifting cradle, and hook it on. Then the two-ton counterweight that brought it down will be shuttled over to the 'up' cable, and sent back to Explorer to be reused. After that's been done ten thousand times, they can lift Titanic . This section of her, anyway."

"Sounds a very roundabout way of doing things," commented one of the VIPs. "Why can't they just use compressed air?" The guide had heard this a dozen times, but had learned to answer all such questions politely. (The pay was good, and so were the fringe benefits.)

"It's possible, ma'am, but much too expensive. The pressure here is enormous. I imagine you're all familiar with the standard scuba bottles - they're usually rated at two hundred atmospheres. Well, if you opened one of these down here, the air wouldn't come out. The water would rush in - and fill half the bottle!"

Perhaps he'd overdone it; some of the passengers were looking a little worried. So he continued hastily, hoping to divert their thoughts. "We do use some compressed air for trimming and fine control. And in the final stages of the ascent, it will play a major role.

"Now, the skipper is going to fly us toward the stern, along the promenade deck. Then he'll do a reverse run, so you'll all have an equally good view. I won't do any more talking for a while -"

Very slowly, Piccard moved the length of the great shadowy hulk. Much of it was in darkness, but some open hatches spilled dramatic fans of light where robots were at work in the interior, fixing buoyancy modules wherever lifting forces could be tolerated.

No one spoke a word as the weed-festooned walls of steel glided by. It was still very hard to grasp the scale of the wreck - still, after a hundred years, one of the largest passenger ships ever built. And the most luxurious, if only for reasons of pure economics. Titanic had marked the end of an era; after the war that was coming, no one would ever again be able to afford such opulence. Nor, perhaps, would anyone care to risk it, lest such arrogance once again provoke the envy of the gods.

The mountain of steel faded into the distance; for a while, the nimbus of light surrounding it was still faintly visible. Then there was only the barren seabed drifting below Piccard, appearing and disappearing in the twin ovals of its forward lights.

Though it was barren, it was not featureless; it was pitted and gouged, and crisscrossed with trenches and the scars of deep-sea dredges.

"This is the debris field," said the guide, breaking his silence at last. "It was covered with pieces of the ship - crockery, furniture, kitchen utensils, you name it. They were all collected while Lloyd's and the Canadian government were still arguing in the World Court. When the ruling came, it was too late - "What's that ?" one of the passengers suddenly asked. She had caught a glimpse of movement through her little window.