Pressure mounts on cruise ship divers

Hope fades to find survivors of cruise disaster
The Costa Concordia cruise ship, run aground at the island of Giglio off the Tuscan coast.

GIGLIO, Italy -- Rough seas were forecast Thursday off the northwest coast of Italy, while divers there resumed the search for victims possibly trapped inside the capsized ocean liner Costa Concordia.

The bad forecast put mounting pressure on the rescue workers looking for 21 people still missing.

The hunt for bodies is tied to growing concern over a possible environmental disaster.

Authorities insist that all the rescuers must be off the ship before an operation to remove the 500,000 gallons of fuel in the ship's tanks begins.

Cruise ship search resumes; 21 still missing
Photos: Cruise ship capsizes
Complete coverage: Costa Concordia runs aground

The massive amounts of equipment that will be needed are already arriving. The specialists who will do the job say the preferred extraction technique is called "hot tapping." The fuel is pre-heated, so tanks can be identified. As oil is pumped out, it is replaced with sea water.

That, says salvage expert Max Iguera of Smit Salvage, enables workers to drill into the tanks without any risks of fuel leaking in the sea, and to then extract the fuel once it's heated.

Anti-pollution booms have been laid between the wreck and the shoreline but local residents whose whole way of life is under threat are worried it won't be enough.

"It will be an environmental disaster," says Elizabeth Nanni, vice president of Giglio's tourism office, "and it would be a commercial disaster for the island's tourism, which is the main source of revenue."