The official death toll in the South Korean ferry sinking has soared to 58 after divers finally succeeded in entering the vessel.

The new toll emerged as a newly released transcript showed the ferry's crew were crippled with confusion and indecision well after it began listing dangerously.

Three times in succession, and about half an hour after the ferry Sewol began tilting on Wednesday, a crew member asked Jindo Vessel Traffic Services Centre (VTS) whether passengers would be rescued if they abandoned ship off South Korea's southern coast.

That followed several statements from the ship that it was impossible for people aboard to even move, and another in which it said it was "impossible to broadcast" instructions. Many people followed the captain's initial order to stay below deck, where it is feared they remain trapped. About 240 people are still missing.

Only 174 people are known to have survived the sinking of the Sewol, which had been on its way from the South Korean port city of Incheon to the southern island of Jeju. The captain initially ordered passengers to stay in their rooms, and took more than a half hour to issue an evacuation order - an order several passengers have said they never heard.

The confirmed death toll jumped from 33 to 58 within 24 hours as divers, hampered for days by strong currents, bad weather and low visibility, finally found a way inside the sunken vessel.

They quickly discovered more than a dozen bodies there in what almost certainly was just the beginning of a massive and grim recovery effort. Some of the bodies found were recovered outside the ship.

The Sewol sank with 476 people on board, 323 of them students from a high school in Ansan. A 21-year-old South Korean sailor, surnamed Cho, also died from injuries he sustained while working on a warship going to help rescue passengers in the ferry, said Commander Yim Myung-soo of the South Korean navy.

The heartbreaking task of ­recovering the bodies led to yet another - identifying them. Information sheets taped to the walls of a gymnasium on Jindo island where families of the missing are staying listed details of the bodies such as sex, height, length of hair and clothing.

Anguished families of the missing, fearful they might be left without even their loved ones' bodies, also blocked the prime minister's car during a visit and attempted a long protest march to the presidential Blue House in Seoul, about 250 miles to the north.

About 100 relatives walked for around six hours before some 200 police officers in neon jackets blocked them from continuing on a main road. The relatives said they wanted to travel to the Blue House to voice their complaints to the president.

The captain, as he was taken from court in Mokpo, had explained his decision to wait before ordering an evacuation. "At the time, the current was very strong, the temperature of the ocean water was cold, and I thought that if people left the ferry without (proper) judgment, if they were not wearing a life jacket, and even if they were, they would drift away and face many other difficulties," Lee Joon-seok told reporters. "The rescue boats had not arrived yet, nor were there any civilian fishing ships or other boats nearby at that time."