Strong currents and poor visibility hampered rescuers in the search for 287 passengers still missing more than 24 hours after their ferry flipped on to its side and filled with cold water off the southern coast of South Korea.
Nine have been confirmed dead but many expect that number will rise sharply because the missing have spent more than a day either trapped in the ferry or in the cold seawater.
There were 475 people aboard and frantic parents have gathered at the high school students' school near Seoul and in Mokpo, in the south of the country, not far from where the ferry slipped beneath the surface until only the blue-tipped, forward edge of the keel was visible.
Parents, siblings and other relatives of three high school students killed in the sinking wailed and sobbed as ambulances at a hospital in Mokpo took the students' bodies to the city near Seoul.
The family of one of the victims, 24-year-old teacher Choi Hye-jung, spoke about a young woman who loved to boast of how her students would come to her office and give her hugs. She loved teaching and her students and was excited about her first-ever school trip to Jeju island. There were 325 students on board, headed to Jeju for a four-day trip.
“She was very active and wanted to be a good leader,” her father, Choi Jae-kyu, 53, said at Mokpo Jung-Ang Hospital while waiting for the arrival of his daughter's body. Ms Choi's mother, sitting on a bench, sobbed quietly with her head bent down on her knee.
Meanwhile, 20 divers tried to get inside the ship's wreckage but could not because of the current, the coastguard said. More than 400 rescuers searched nearby waters overnight.
“We cannot give up,” said president Park Geun-hye, after a briefing in Seoul. “We have to do our best to rescue even one passenger.”
The coastguard said it found two more bodies in the sea this morning, pushing the death toll to nine. The two were believed to be men in their 20s and 30s but authorities are trying to confirm their identity, said an official from the coastguard's press team.
Dozens were injured, and coastguard officials put the number of survivors at 179.
It is still unknown why the ferry sank, but coastguard officials are interviewing the captain and crew. The Sewol, a 480ft vessel that could hold more than 900 people, set sail Tuesday from Incheon, in north-western South Korea, on an overnight, 14-hour journey to the tourist island of Jeju.
The ferry was three hours from its destination when it sent a distress call after it began listing to one side, according to the Ministry of Security and Public Administration.
Passenger Kim Seong-mok told broadcaster YTN that after having breakfast, he felt the ferry tilt and then heard it crash into something. He said he was certain that many people were trapped inside the ferry as water rushed in and the severe tilt of the vessel kept them from reaching the exits.
Oh Yong-seok, a 58-year-old crew member who escaped with about a dozen others, including the captain, told the Associated Press that rescue efforts were hampered by the ferry's severe tilt.
“We couldn't even move one step. The slope was too big,” he said.
The Sewol's wreckage is in waters a little north of Byeongpung Island, which is not far from the mainland and about 290 miles from Seoul.
TV stations broadcast live pictures of the listing Sewol as passengers clambered over the side, jumped into the sea or were hoisted up by helicopters. At least 87 vessels and 18 aircraft swarmed around the stricken ferry.
The water temperature in the area was about 12C, cold enough to cause signs of hypothermia after about 90 minutes of exposure, according to an emergency official.
Lee Gyeong-og, a vice minister for the Public Administration and Security Ministry, said the ocean was 120ft deep in the area.
The survivors - wet, stunned and many without shoes - were taken to nearby Jindo Island, where medical teams wrapped them in blankets and checked for injuries before taking them to a cavernous gymnasium.
As the search dragged on, families of the missing gathered at a nearby dock, some crying and holding each other. Boats circled the sunken ferry into the night, illuminated by red flares.
The numbers of passengers, as well as the dead and missing, fluctuated throughout the day. As of early Thursday, South Korean authorities estimated 475 people were on the ferry.
Of that total, there were 325 students and 15 teachers from Danwon High School in Ansan, a city near Seoul. They were heading to Jeju for a four-day trip, according to a relief team set up by Gyeonggi province.
Authorities said the dead included a female member of the crew and two male students.
The Sewol, which travelled twice a week between Incheon and Jeju, was built in Japan in 1994 and could carry a maximum of 921 people, 180 vehicles and 152 shipping containers, according to the Yonhap news agency.