Giglio, Italy (CNN) -- A boat's horn bellowed 32 times off the coast of Italy on Sunday, honoring each of the victims who died a year ago when a luxury cruise liner ran aground.
Family members of those who perished tossed wreaths, lilies and notes into icy waters at a ceremony marking the anniversary of the Costa Concordia crash. And a large boulder bearing a plaque with victims' names was lowered into the same sea that claimed their lives.
The somber memorial was a sharp contrast to the chaos of a year ago, when the massive ship ran aground with 3,200 passengers and 1,000 crew members on board.
According to passengers' accounts, pandemonium erupted as guests rushed to fill the lifeboats and escape the ship. Some crew members helped passengers and then jumped overboard; remaining members seemed helpless to handle the melee.
The night of the accident, many survivors sought shelter in churches and other buildings on the tiny Tuscan island of Giglio.
At one of the churches on Sunday, many survivors and family members of victims gathered for a two-hour Mass to remember the victims and honor divers and rescue workers.
"I came to pray for my colleagues and the passengers who lost their lives," said Santosh Velhal, a Costa Concordia crew member from Mumbai who worked in the ship's security department.
The children of Gerald and Barbara Heil -- an American couple from Minnesota who died in the accident -- were also among those who traveled to Italy for Sunday's ceremony.
The day's events also included the dedication of a plaque with the victims' names on a wall in Giglio's harbor and a violin concert held in a local church. At 9:45 p.m., the exact one-year anniversary of the moment of impact, survivors planned to light 32 lanterns -- one for each of the victims.
Meanwhile, the Costa Concordia, now a half-submerged carcass, still sits in the harbor where it ran aground. Hundreds of people are working 24-7 to secure it, but salvage efforts are taking longer than expected. Officials now hope to have the ship upright by late June or early July and to tow it to some port by September.
During Sunday's ceremony, the skies were overcast and a fierce wind blew.
The seas were rough, and the waves washed up against the wreckage and salvage barges with such force that crews had to reinforce their equipment.
"Thank God the weather wasn't like this last year," Karin Fogazzi told reporters as she stared at the wreckage.
The weather was more temperate last year, when she and her husband Roberto escaped the ship carrying their 10-month-old son Daniel down a rope ladder.
The family came on Sunday to mark the occasion, she said, and to try to help deal with the post-traumatic stress disorder they've been battling over the past year.
The Concordia's captain, Francesco Schettino, could face charges that include manslaughter and abandoning ship. Other crew members and Concordia executives also could face trial.
Schettino has said that managers of the cruise line instructed him to sail close to the island and has denied allegations that he was sailing too fast. He said the rock the ship struck was not indicated on his charts of the area.
In an interview with Italy's "Domenica In" television show on Sunday, Schettino blamed the ship's helmsman for misunderstanding orders to avoid the rocks. The captain said he'd felt pain over the victims' deaths every day for the past year.
The day was a somber reminder of the lives lost in the shipwreck, but it was also important for the 900 residents of Giglio to commemorate an event that changed their island forever.
"This is not a celebration," Mayor Sergio Ortelli said. "This year has been dramatic for the people of this island who have had their whole lives turned upside down by this event. We hope our island returns to a place of tranquility once the steel monster out there is towed away."
CNN's Catherine E. Shoichet contributed to this report.