The coast guard of South Korea said Thursday that it is investigating the details of the last hours of a ferry which sank on Wednesday with hundreds of students on board.
Nine people were killed and 287 are missing, while 179 were able to be rescued.
Officials could not confirm reports that the crew delayed giving orders to abandon ship and launch the lifeboats.
Strong currents have hampered the work of divers.
The South Korean President, Park Geun-hye, met with relatives of the missing at a nearby port.
The role of captain is not clear. At a police station, he merely said that he was sorry for what had happened and was deeply embarrassed.