Inside the Costa Concordia, rescue divers have restarted their search for the 21 people still missing on Thursday, but a forecast for rough seas means they'll need to work fast.

With only a slim hope that the missing will be found alive, rescuers combed the fourth level of the ship. Experts from the Italian Navy are planning to blow more holes in the Concordia's hull with explosives to gain better access to areas of the boat.

The search had been suspended on Wednesday after the boat began to shift position. It is perched on submerged rocks, but adverse weather could move the boat and possibly rupture its fuel tanks.

Once the rescue efforts are completed, salvage boats from a Rotterdam-based company are prepared to begin pumping the Concordia's 500,000 gallons of fuel, hopefully preventing an environmental disaster.

They'll be drilling into each tank, and pumping the oil out and putting it into a barge or a coastal tanker or even a tug, Mike Lacey, of the International Salvage Union, told the BBC.

These things are all very weather-dependent. If the weather turns against them, then they won't be able to work. So I understand they expect to take a week to two weeks to get all the fuel off.

Victims Identified  

Italian authorities have identified four more of the victims as Peruvian crew member Thomas Alberto Costilla Mendoza; Italian passenger Giovanni Masia; and French passengers Francis Servil, 71, and Jean-Pierre Micheaud, 61. Two other French nationals and a Spanish passenger were identified earlier in the day. A total of 11 people are confirmed dead.

The official missing persons list includes 12 Germans, one Indian man, five Italians and Americans Barbara and Gerald Heil -- all passengers -- and Italian crew member Giuseppe Girolamo.

“It’s important to continue our search. Family members find it important to have the body of the loved one they’ve lost because it gives them closure. We understand this,” Modesto Dilda, head of the firefighters diving team from the city of Vicenza, told the National Post.

The Costa Concordia capsized on Friday night after captain Francesco Schettino brought the ship off course and ran aground near the coast of Giglio. Because the ship was tilted so severely, the life rafts were submerged, but the Italian Coast Guard managed to get most of the 4,200 passengers and crew members to safety.