Eighteen months ago the massive Costa Concordia cruise liner crashed onto the tiny island of Giglio, 12 miles off Italy's western coast. Within minutes the 950-foot vessel tipped sideways, tossing passengers into the sea. In the end, 32 people died and 64 were seriously injured.

In the very near future, engineers will attempt to pull the battered ship upright and float it away. The hulk is snagged on jagged outcroppings of rock in 60 feet of water, groaning and swaying precariously with each incoming wave on the edge of a steep slope that drops 200 feet to the bottom of the sea. If the operation goes well, it will be the greatest success in the history of maritime salvage. But if a single thing goes wrong, the boat will tear apart or sink whole, seriously polluting the Pelagos Sanctuary for Mediterranean Marine Mammals—the largest park of its kind in Europe—which surrounds Giglio. The waters are a haven for dolphins, porpoises, whale calves and scores of other sea creatures. Exquisite coral reefs line the seafloor immediately below the stranded, rusting ship.

Although reclaimers siphoned the fuel from Concordia's tanks, the six mammoth Wärtsilä engines still hold volumes of diesel fuel and oily lubricants, as does the engine room, all of which would be released into the pristine waters if the ship went down. So would thousands of gallons of chemicals, from cleaning supplies to paints, each container burst by water pressure. And the vessel was stocked to feed 4,229 people for 10 days when it left port just three hours before it sank, much of the food inside freezers that would decompose. Tons and tons of ship metal would leach and corrode.

Shipwrecks this big are usually blown up or sunk. But Italy's environmental ministry backed the people of Giglio in pressuring Costa Cruises to right the vessel and float it to the mainland, to preserve the island's pristine shore and waters. Also, once the boat is recovered, police will investigate its watery innards—a crime scene that may hold evidence against Captain Francesco Schettino, who is charged with manslaughter and abandoning ship. Two bodies have still not been recovered. After the investigation, the hulk will be disassembled.

The recovery operation falls to a charismatic, 51-year-old freelance salvage master from South Africa named Nick Sloane, well known in the industry and not exactly averse to risk. Hired by the two companies that have the recovery contract—Florida-based Titan Salvage and Italian firm Micoperi—Sloane has worked on some of the largest maritime accidents in the world. He has a file of photographs on his iPhone depicting all the ships he has detonated in his long career.

This time, however, no explosives will be involved. Sloane and his team will employ a procedure known as parbuckling. Cables and pulleys will slowly tug the colossal vessel off the rocks and set it upright [see illustrations on next two pages]. As the ship becomes vertical, it will land on six massive underwater platforms made of more steel than was used to build the Eiffel Tower. Sloane estimates that the pulling process will take eight hours, during which time his crew will have control up to a certain point. “Then gravity will take over,” he says. “If we've done this right, the ship will right herself and rest on the platforms.”

If they have not done it right, the platforms may break, and the ship will scrape its way down the underwater slope, shredding and crushing the corals and sea grasses as it slides into the depths. The other danger is that the 114,000-metric-ton ship will come apart under its own weight as it is pulled upright, spilling its toxic contents into the fragile aquatic ecosystem, which has already suffered immensely from the noise and pollution of the salvage operation. “The exterior of the ship was not built to be lifted like this,” Sloane says. “When she is lifted, you will hear the twisting and breaking apart of her inner section, but hopefully the outer shell will stay intact.” His crew has spent months reinforcing that shell. “Nothing like this has ever been attempted before,” Sloane told Scientific American on a private tour around the wreck and the salvage rigs. “But the more you plan and prepare, the luckier you get.”

Even if Sloane succeeds, the work will not be over. The salvage contract demands that the environment be returned to its original state. The large steel platforms will have to be removed, and every hole drilled into the sandy floor for pillars that hold the platform will have to be filled. Sloane wanted to leave the structures in place as a site for a salvage school. But the people of Giglio do not want any trace of the accident to remain as a reminder of the day their idyllic island was marred.