Jindo, South Korea (CNN) -- Like the fog that continued Friday to envelop the perilous search-and-rescue zone, rising anger and desperation shrouded those waiting for word on their loved ones still trapped on a capsized South Korean ferry.
Those massing on the dock in the Jindo, South Korea, harbor -- about 20 kilometers (12 miles) from where the five-story ship sank -- were not giving up, especially after authorities granted the possibility some if not all the 271 missing people could have survived thanks to air pockets two days after the vessel's sinking.
Yet Thursday's search, and the still dreary conditions on Friday, didn't give them much hope.
No survivors were rescued over a 24-hour period, during which time U.S. Navy Capt. Heidi Agle said two Navy helicopters equipped with special radars could only fly a few hours due to the poor weather. Divers in the water battled against strong currents, frigid water temperatures in the 50s (10 to 15 Celsius) and general murkiness that made seeing, much less rescuing anyone, challenging.
"It's extremely difficult," Agle, who said the Navy helicopters were from a U.S. carrier nearby, told CNN's Wolf Blitzer. "There are heavy currents in the area, so the vessel itself is not stable in the water. So you are, by default, putting divers at risk... There are many, many things that are working against them."
It's a different kind of struggle for those in Jindo, many of them the parents of more than 300 Seoul high school students who'd been heading to a four-day island holiday.
Wearing ponchos to fend off rain, some of them could be heard crying in the face of the grim situation. Others expressed anger at information such as the fact few of the ferry's lifeboats were deployed, and reports that its captain -- shortly after loudspeaker announcements had urged passengers to go to their cabins deep inside the ship -- was among the first off the ship.
From the dock, the relatives made loud and clear they wanted him to give them answers
They chanted, "Captain, come out."
He didn't talk directly to them, but ferry Capt. Lee Joon Suk did emerge Thursday at a South Korean Coast Guard office. His head and face covered, he broke down in tears when reporters asked him if he had anything to say.
Lee managed only, "I am sorry, I am at a loss for words."
25 confirmed dead; hundreds still missing
As of Friday morning, the east Asian island nation's coast guard reported 25 confirmed dead. There are fears that toll could spike as time passes, with the prospect of hypothermia and lack of oxygen doing in those that might have made it past when the ship initially turned over.
At least 179 people were able to make it off in time.
Authorities continued to operate under the assumption there are more survivors, hoping that trapped passengers found pockets of air. Images show parts of the hull visible above water and presumably not flooded.
"Absolutely, there could be areas in there where there is breathable air, but the trouble right now is the temperature and getting people to them," Mike Dean, the U.S. Navy deputy director for salvage and diving, told "CNN Tonight."
More than 170 ships and more than 500 divers have swarmed the ferry site, though they are hampered by relentless rain, whipping winds and thick fog in addition to strong currents and murky waters.
Three divers who joined the search went missing in high tide but were later found, CNN affiliate YTN reported. And efforts to pump air into the ship failed because of the bad weather.
More such attempts to pump in air are expected Friday. Authorities are "leaning toward" using a crane to raise the vessel, according to Kim Soo Hyeon, the chief of South Korea's Yellow Sea Maritime Police Agency.
Two cranes had arrived at the scene early Friday, with a third scheduled to be there later in the day.
Still, there was no guarantee any of those efforts would lead to rescues.
Despite government assurances that rescuers would work around the clock to save lives, some relatives were angry about the pace of the operation.
"If the government cares for the people, our family, our children, please rescue our families and our children," said Chang Min, whose second-grade son is among the missing.
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