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.
As those efforts continued, evidence was growing that human error contributed to the accident, one of South Korea’s worst disasters in recent decades.
Kim Su-hyun, a provincial coast guard chief, told reporters on Thursday that the ship’s captain, Lee Jun-seok, stood accused of violating his responsibilities by abandoning the ferry ahead of most of his passengers. Coast guard officials who questioned Mr. Lee on Thursday said they were reviewing possible criminal charges, while the police said they were investigating whether he had escaped aboard one of the few life rafts used.
On Friday, Park Jae-uk, a senior investigator, said that Mr. Lee was not on the bridge at the time of the accident and left control of the ship to his third mate. “We are investigating where exactly he was at the time,” Mr. Park added.
Mr. Lee made a brief appearance before reporters on Thursday. “I can’t lift my face before the passengers and family members of those missing,” he said. But he provided little clarity on what led the 6,825-ton Sewol to lean so far to its side before sinking, and why so many aboard had been unable to escape.
For some maritime experts, the captain’s decision to abandon the ship and the crew’s emergency performance seemed to echo problems in the wreck of the Costa Concordia, an Italian cruise ship that ran aground in 2012, killing 32 people.
James T. Shirley Jr., an accident investigator in Newtown, Pa., said that in the two and a half hours it took the ship to sink, the crew “certainly had enough time to get most of the people off.”
“I don’t understand why the crew would be instructing passengers to stay inside the ship,” Mr. Shirley said. “I would think that if nothing else, they would be getting them outside with life jackets on so if it sank, they could at least get into the cold water with their jackets.”
Capt. William H. Doherty, a maritime safety expert at Nexus Consulting Group who commanded Navy and merchant ships, said there was “clearly a breakdown in safety training” on the South Korean ferry, a failure he said could be attributed to its officers and to Korean regulators.
“When they issued a safety certification for the ship, they had to certify that the crew was trained,” Captain Doherty said, noting the communications officer’s admission that he had not taken part in an evacuation drill. “You have to satisfy yourself that this crew is trained in all emergency situations.”
For the 325 students from Danwon High School who made up the bulk of the passengers, it was a trip they had been eagerly awaiting, a last chance for fun before a grueling year of studying for South Korea’s university entrance exam. Soon after the ferry left the port of Incheon on Tuesday night bound for the resort island of Jeju, they celebrated by launching fireworks from the deck.
According to survivors, the students were having a morning break after breakfast on Wednesday, roaming through the floors and snapping pictures on the deck, when the ship began tilting.
“I don’t remember that there was any safety instruction before we boarded the ship,” said Kim Su-bin, 16, a Danwon student who survived by climbing out of the sinking ship and jumping into the water. “Life jackets were on the fourth floor where the sleeping cabins were, but those who were on the third floor at the time had no life jackets.”
Investigators said the Sewol appeared to have made a sharp turn to the left around the time it began to tilt. It had been sailing slightly off its usual course, they said. It was unclear why such a turn was tried in waters known for their strong currents, or why the turn had caused the ship to lean.
Inside the ferry, chaos unfolded, survivors said, as the walls and floor seemed to exchange positions. Bottles and dishes fell. The ship’s twisting stairways became almost impossible to negotiate. Passengers were tossed to one side. Trays and soup bowls overturned, said Song Ji-cheol, a college student who worked part-time in the cafeteria.
“All of a sudden, we were submerged,” he said. “I tried to hold on to the tables, but they were moving around, too.”
At some point, survivors said, the lights went out.
“When the ship began tilting, there was a thudding noise, and I thought it was the noise made by students bumping into the walls,” Han Hee-min said on Thursday in a hospital in Ansan, the city south of Seoul where Danwon High School is. “I had a life jacket, so I floated. Some friends grabbed my leg, and I don’t know what happened to them.”
The communications officer, Mr. Kang, 32, said that he and another crew member had been forced to make a quick decision. They thought that if passengers fled in a panicked rush, it could make matters worse, he said.
Shin Seong-hee, a Danwon student, was among those who heeded the advice. In a text message she sent to her father, she said the crew had told her that “it was more dangerous to move.”
Her father texted back, “I know the rescuers are coming but why don’t you try to come outside?”
“I can’t because the ship is tilting too much,” she said, in a text displayed by her sister. Ms. Shin has not been heard from since.
Some survivors gave accounts of professionalism and self-sacrifice by crew members. Kim Su-bin, the Danwon student who climbed out and jumped into the water, thanked Park Ji-young, a crew member who was found dead on Wednesday, for calming students and staying behind without a life jacket after helping students escape.
“Bring my child back alive!” some parents yelled on Thursday when President Park Geun-hye visited a gymnasium that local officials had turned into a shelter for grieving families. Ms. Park promised “all available resources” for the rescue efforts, and “a thorough investigation and stern punishment for those responsible.”
An editorial in the country’s leading conservative daily newspaper, Chosun Ilbo, which has been mostly supportive of Ms. Park’s government, denounced it for “floundering.”
“Above all, the people must have felt deeply that South Korea is a country that doesn’t value human lives,” it said. “Hundreds of passengers sank with the ship, but its captain and most of its crew came out alive.”