That was in 1997 in the Bismarck Sea off Papua New Guinea, 30 miles north of the small port of Rabaul. There, between the islands of New Britain and New Ireland, Scott and Binns discovered two large volcanic mounds stretching to within two-thirds of a mile of the sea surface. A local geologist who had joined the expedition named them North Su and South Su, su being the word for “breast” in the local tongue. (Lonesome male explorers tend to compare mountains to mammaries; the Grand Tetons are perhaps the most pointed example.) On both mounds a submersible video camera showed puffing black smokers surrounded by dense clumps of snails, mussels, and crabs—the kind of rich fauna that has made seafloor hot springs so fascinating to biologists and the public.

But Binns and Scott were more fascinated by the rocks that they dredged from the mounds, which were rich in a different way. They contained copper and gold concentrations several times higher than those typical of mines on land.

A press release went out while their ship, the Franklin, was still at sea. By the time it put into Cairns, Australia, TV cameras were waiting, and so was Julian Malnic, who was there to report the story. After interviewing Binns, Malnic decided that it made less sense to write about this patch of seafloor than to stake a claim to it. Through contacts in the Papua New Guinean government, he managed to do just that. His was the first exploration claim to a seafloor sulfide deposit, and it was the beginning of Nautilus Minerals. By the time Heydon joined the company, the economic booms in India and China were starting to drive copper prices to a record $4 per pound (compared with about $1 a pound today). Drug addicts in the United States and abroad were stealing copper pipes from air-conditioning units and irrigation systems. The interest in new sources of copper was sky-high; the interest in gold is always high.

Compared with manganese nodules, the seafloor sulfides associated with hydrothermal vents have a huge advantage: They are much easier to get to. Whereas the nodules are scattered across the deep abyssal plains of the oceans, hundreds of miles from shore and typically three miles or more below the surface, many of the sulfide deposits are close to a coastline; also, they are always on undersea mountains and therefore located in much shallower water.

The deposit Nautilus plans to mine, called Solwara 1, lies on the north slope of North Su, an active volcano, and it is less than a mile below the surface. Oil companies have drilled in water twice that deep. Nautilus’s plan is to follow the technological path that oil rigs have already blazed into the deep sea.

“We’re lucky,” says Steve Rogers, a former offshore oil engineer who succeeded Heydon as Nautilus CEO last June. “The oil and gas industry has spent a lot of money developing these technologies. I suppose it’s a little surprising that the mining industry hasn’t tapped into it before—but we are here now.”

Nautilus’s mining scheme consists of a dedicated ship, a mile-long riser pipe, and a “seafloor mining tool,” a huge tethered robot that will strip-mine the seafloor under remote control. The oil industry uses similar robots to dig trenches for pipelines, but the one Nautilus has commissioned from a British firm called Soil Machine Dynamics will still be remarkable. It will be the size of a two-story house—a house that will be able to walk on four legs across the rough volcanic terrain until it has smoothed that terrain into a series of flat steps, as in strip mines on land. At that point the legs will retract and the mining robot will move about on more efficient tank treads. A large, drum-shaped cutting tool at the end of a long boom will be able to cut up to 6,000 tons of sulfide rock a day from the seafloor, chopping it into nuggets of an inch or less. Sonar on the machine will allow the operator to position it to within an inch; sonar is essential because video cameras will not be able to see through the thick cloud of mud and pulverized rock the robot will be kicking up.

A six-foot-wide suction mouth positioned directly behind the cutting head will pump a slurry of ore and seawater into the foot-wide riser and up to the ship. On board the ship, screens and centrifuges will separate out the solids, which will be transferred to barges and carried to Rabaul; the water will be pumped back down to the seafloor. The ship will remain in its first location for two or three years, or however long it takes to mine out Solwara 1. The deposit there is about 1,500 meters long by 100 meters wide (about a mile long and 300 feet wide), but Nautilus cannot say how deep it is—except that in many places it is deeper than the 20-meter (about 65-foot) exploratory holes that the company has drilled into it.

There are at least 2.2 million metric tons of ore to be recovered, according to Nautilus, and that ore is richer even than Scott and Binns thought: It contains around 7 percent copper and around 6 to 8 parts per million of gold. On land today, Rogers says, “you would be pretty excited if you had 1 percent copper, and 6 to 8 grams per ton of gold would be a gold mine in itself.” Most of the ore at Solwara 1 is right at the base of the seafloor. To get at it Nautilus will have to remove a mere 130,000 tons of overburden mud, a bagatelle by mining industry standards. And once the deposit is mined out, the company will simply pack up robot and riser and steam to the next location. Unlike a mining company on land, Nautilus will not leave behind an infrastructure of roads and buildings.

The company will, of course, leave behind a damaged seafloor—but the environmental costs, too, will be less, Nautilus insists, than those of a comparable mine on land. “If we accept that the world’s demand for metal is going to continue to rise, we need to get metals from somewhere in an environmentally responsible way,” says Samantha Smith, a biologist who managed the company’s environmental impact assessment. In strip-mining a bit less than 30 acres of seafloor, Nautilus will consume hydrothermal chimneys and wipe out the clusters of snails and barnacles, crab and shrimp that are nourished by their sulfide emanations. But some of the chimneys will regrow, Smith says—mining cannot snuff out the underlying volcano—and the animals are expected to return within a few years. Black smokers are by nature ephemeral, so the animals there are adapted to colonizing new springs as old ones wink out. To encourage that process, Nautilus intends to leave the hot springs on South Su, a little over a mile away, untouched, as a seed stock.

With the help of Cindy Van Dover, a Duke University biologist and expert in hydrothermal vents, Nautilus is even studying the possibility of picking up snails and barnacles in the path of the mining tool and transplanting them to a temporary haven, to be brought home when the coast is clear. “Their environmental sensitivity is pretty darn good,” Van Dover says. “They came to us and asked, ‘How do we do this right?’” She chaired a committee convened by the International Seabed Authority to draw up recommendations for the mining of black smokers in international waters. Although Solwara 1, the first case in point, lies in Papua New Guinea’s waters, Nautilus seems to have followed the authority’s recommendations anyway, she says.

Yet like many marine scientists and environmentalists, Van Dover would prefer that the seafloor not be mined at all. So little of it has been explored, she says, and it is so much harder than on land to see what is going on that there is no way to be sure that mining is not extinguishing species; we haven’t had time to discover the snail darters and spotted owls.

“It would be as if Lewis and Clark went out and found Yellowstone, and a couple of years later the mining companies said, ‘We are going to strip-mine it,’” she says. But not, it seems, for at least a few years.

Last June, speaking from London on the very day he signed a deal to have his mining ship constructed in Turkey (and right after he had taken over the reins from Heydon), Rogers saw no clouds on Nautilus’s horizon. Then again, not many people saw the economic storm coming. Copper prices, which had quintupled during the period in which Heydon was raising money for the company, collapsed during the second half of last year. By December Nautilus’s stock on the Toronto exchange had fallen below a Canadian dollar per share after peaking in 2007 at more than six dollars. Gold prices remained high—as they typically do in economically troubled times—and in principle, says Scott Trebilcock, the company’s vice president for business development, the Solwara 1 project remained economically viable. With the credit crash, however, Nautilus had no prospect of getting the extra funds it needed to bring the ore to market.

A week before Christmas the company announced that it was postponing the construction of all its equipment, including the mining ship, and laying off 30 percent of its staff. It planned to continue engineering and public relations work and also exploring for new sulfide deposits. But it could no longer predict when it would begin mining. That would largely depend on when the economic storm blew over.

As the company he built hunkered down, David Heydon was back in Brisbane, having left Nautilus in June when the company was riding high. He has since started two new companies. With one he is hoping to get in on the ground floor of the old ocean-bottom manganese-nodule business, version 2.0, which he thinks is poised to take off in a decade or so. With another company Heydon is hoping to harvest underwater wood; he believes that there is a lot of valuable hardwood trapped in patches of tropical rain forest that were inundated by hydroelectric dams. “The bit that I like is the start-up phase,” Heydon says.

And the true believers are not giving up on the incredible mineral potential of the black smokers. Steve Scott, one of the men who discovered the Solwara 1 deposit, remains convinced that one day soon—though apparently not in 2010—it will become the site of the first deep-sea mining project. “It’s as sure a thing as you’re ever going to find in the mining industry,” he says.

On the other hand, as Scott himself points out, it was a quarter century ago, in 1984, that he first predicted seafloor sulfide deposits would be mined one day. “I’m still waiting,” he says.