When the ship is upright, caissons will be fixed to the other side of the hull to stabilize it.

CNN: Wrecked Costa Concordia to be raised from Italian sea bed

Two cranes fixed to the platform will pull the ship upright, helped by the weight of the caissons, which will be filled with water.

CNN: Wrecked Costa Concordia to be raised from Italian sea bed

Finally, the caissons on both sides will be emptied, after the water inside has been purified to protect the marine environment, and filled with air, Costa said.

CNN: Wrecked Costa Concordia to be raised from Italian sea bed

First, once the ship has been stabilized, an underwater platform will be built and watertight boxes, or caissons, fixed to the side of the ship that is above water.

CNN: Wrecked Costa Concordia to be raised from Italian sea bed

In addition, rebar casing was punched 165 feet into the bedrock and encased in concrete, and 18 caissons and 54 piles were also utilized to provide stability to the building.

FORBES: Connect

Once upright, more caissons will be attached to the side that had been submerged, and the water in them will then be replaced with air to give buoyancy and allow the wreck to be towed away.

BBC: Salvaging the Costa Concordia