Dubbed the biggest salvage job in history, the wreck of the Costa Concordia has completed its final voyage to Genoa from the island of Giglio where it grounded in January 2012.

The £1billion salvage operation relied heavily on the expertise of Falmouth-based marine drilling experts Fugro Seacore, who were enlisted to shore up the precarious site by installing a vast underwater table bigger than three rugby pitches.

The job was one of the toughest the company had undertaken in its 38 year history.

The table was built of three platforms, each weighing more than five jumbo jets. 

To secure the legs, Fugro Seacore drilled precise holes up to 14 metres into the hard rock under the sea-bed and inserted foundation piles two metres in diameter.

The installation needed to be designed and completed quickly, to prevent the wreck sliding to greater depths and allow work to begin on raising the cruise ship before it broke up, which would result in an environmental disaster.

But with the heavy platform sections needing to fit onto the legs exactly, accuracy was also paramount, with a margin for error of less than 10cm, and just one degree from vertical.

Fugro marine services manager Sam Whitaker explained: “We've done some tough jobs over the years, and this was up there with the toughest. Nobody has ever attempted anything like this before, so we had to design and build the whole thing from scratch. 

“Quite aside from anything else, the 45-degree slope and the sheer hardness of the granite sea-bed made drilling a real challenge.

“Thankfully, when it comes to drilling big, precise holes in granite, you can't get better than a Cornish engineer.”

A 12-strong team from Falmouth, Helston and Penzance worked around the clock to complete the work, capturing waste from the drill to avoid damaging endangered underwater species.

Sam Whitaker continued: “We were drilling up 600 cubic metres of waste every hour, and everything needed to be completely sealed – and ready to shut down at a moment's notice – to protect the sensitive environment.”