(CNN) Efforts have begun to recover the Sewol ferry from the sea off South Korea, three years after it sank killing 304 people, mostly students.

Ordered by the interim government, the planned recovery follows the impeachment of former President Park Geun-hye whose handling of the disaster attracted intense criticism.

Engineers will attempt to lift the 140-meter long ferry from the water without having to cut it into pieces. Doing so will help recover the nine bodies believed to be still trapped inside.

The operation

1. Engineers will attempt to place buoyant "lifting beams" and pontoons underneath the ferry. If the ferry starts breaking apart, recovery experts are expected to halt the process.

2. Cables or "slings" will be attached to the lifting beams.

3. Using the "strand jack system" the cables will winch the ship towards the surface.

4. The ship will be lifted until it is 13 meters above the water.

5. It will then be attached to a barge and towed to shore.

Prayers

On a boat watching the recovery operation, family members were cautious, many having witnessed previous efforts fail.

"I came here today thinking I may be able to see the ship where the soul of my son is buried," said Lim Young-jae, whose son died in the disaster.

Lim said he wanted the vessel to be recovered "so the truth can finally be revealed."

Park Yoon-su, whose daughter survived the sinking, said he would only believe the ship had been recovered when he sees it with his own eyes.

Shin Chang-sik lost his son in the Sewol ferry disaster.

"It's taken too long to get it out of water," he said. "I'm worried that a lot of evidence has already been destroyed or lost, and we won't be able to discover the truth."

Shin Chanh-sik said he has visited the site of the disaster many times after his son's death.

"(The government) has tried about seven or eight times to lift it, but have not succeeded so I'm calmly waiting and watching the process," he said.

"I'm praying for it to work today, especially for the families who still haven't found their lost loved ones."

Family members of Sewol ferry victims gather in front of a lighthouse near the site of the sunken vessel.

Bereaved families gave an emotional press conference Wednesday at the jetty of Paengmok Harbour in Jindo in front of a lighthouse painted red with a yellow ribbon, the symbol of the ferry disaster.

Thousands of yellow ribbons are still tied to the railings, with photos, drawings, messages and prayers from well wishers.

Park Eun-mi, whose daughter has never been found, gave an emotional speech, reading from papers with her voice frequently cracking.

She said she hoped that the bodies would soon be returned, adding that it was "miserable for the families to know where the bodies are but not being able to find them."

National trauma

The passenger ferry sank off the southwest Korean coast on April 16, 2014. As the country watched live broadcasts in horror, more than 300 passengers -- most of them high school students on a field trip to the holiday island of Jeju -- drowned.

A later investigation found evidence of negligence by the coast guard , and in the actions of the crew and captain on the day.

Video emerged of Captain Lee Joon-seok, dressed only in his underwear, leaping into the arms of the Korean Coast Guard as hundreds remained trapped on the vessel. He was later convicted of murder.

Family groups and opposition politicians have long called for the Sewol's recovery and a full investigation of its sinking.

The incident was a black mark on the presidency of Park Geun-hye, who appeared to be absent during the unfolding disaster, not addressing the nation until seven hours after the ferry began taking on water.

Park's impeachment this month for abuse of power was a bittersweet moment for many Sewol families , as the President's handling of the incident was thrown out by a constitutional court as a reason for her impeachment.

Following her ouster, protesters sang a song, "The Truth Never Sinks", commemorating the victims of the ferry disaster.