The day-long commemoration began this morning with the return to the sea of the rocks that ripped open the hull of the cruise liner when it ran aground in the shallows off the west coast of Italy.
It will be followed by a Mass and a minute's silence at 9.45pm tonight at the moment when the vessel hit the rocks.
As previously reported on Afloat.ie, an Irish couple were among the thousands rescued from the ship when it capsized off Tuscany on the evening of 13 January 2012.
The ship's crew have been praised for their efforts during the dangerous night-time evacuation of the sinking ship, and received the Lloyd's List Seafarer of the Year award for their "courage and professionalism".
Meanwhile, the ship's captain Francesco Schettino is under house arrest awaiting trial on charges of manslaughter, causing the incident and abandoning ship.
And BBC News reports that the wreck of the Costa Concordia is expected to be removed from the Tuscan coast by September this year.