JINDO, South Korea — The captain was among the first to flee. Only a couple of the 44 life rafts aboard were deployed. The hundreds of passengers were instructed over the intercom to “stay inside and wait” as the ship leaned to one side and began to sink, dragging scores of students down with it.

“I repeatedly told people to calm themselves and stay where they were for an hour,” Kang Hae-seong, the communications officer on the South Korean ferry that sank on Wednesday, said from his hospital bed. He added that he could not recall taking part in any evacuation drills for the ship, and that when a real emergency came, “I didn’t have time to look at the manual for evacuation.”

It took two and a half hours for the ferry, the Sewol, to capsize and become submerged in the blue-gray waters off the southwestern tip of South Korea. Yet in that time, only 179 of the 475 people believed to have been on board were rescued. By Thursday evening, the confirmed death toll was 25.

By Friday, the vessel was completely submerged. But rescue divers, after two days of futile attempts, succeeded in swimming into the ship, though it was unclear how far they were able to enter. Rescuers were using high-pressure hoses to pump oxygen inside the ship, in the hope that some of the 271 people still missing, most of them students, might have survived in air pockets inside the overturned vessel.