JINDO, South Korea (AFP) - Divers were battling atrocious weather conditions and powerful swell on Sunday in their grim search for corpses believed trapped in the sunken South Korean ferry, a coastguard spokesman said.
Rolling seas whipped up by strong winds were badly complicating efforts to find the remains of more than 100 people still unaccounted for 11 days after the Sewol capsized with 476 people - many of them schoolchildren - on board.
On Saturday four more of the ship's crew were arrested. All 15 surviving mariners are now in custody and face charges ranging from criminal negligence to abandoning passengers.
Despite waves up to three metres (nine feet) tall and near gale-force winds, teams of divers were still trying to get into the ferry.
"The situation is very difficult due to the weather, but we are continuing search efforts, using the occasional calmer periods," a coastguard spokesman said, adding 93 divers would take part in Sunday's operation.
Heavy seas prevented divers from getting into the ship on Saturday.
Forecasters warned wind and rain would pick up throughout the day.
"There is a possibility that a high wave advisory will be issued in sea areas around Jindo Sunday afternoon," Yonhap news agency quoted a weather service official as saying.
The confirmed death toll from the tragedy stood Sunday at 187, with 115 unaccounted for.
Making up the bulk of the passengers on the 6,825 tonne Sewol when it sank were 325 high school students - around 250 of whom are either confirmed or presumed dead.
Although all hope of finding survivors has been extinguished, there is still anger and deep frustration among relatives of the missing over the pace of the recovery operation.
Frogmen - who were unable to get inside the ferry for the first two days - have battled strong currents, poor visibility and blockages.
The conditions each mission can be no more than a few minutes in length.
But even in this short time, they are coming across scenes of horror in the murky water, including one dormitory room packed with the bodies of 48 students wearing lifejackets.
Around a quarter of the dead recovered so far have been found in waters outside the sunken vessel, and there are fears that some of the missing may have drifted free from the wreck.
That could be exacerbated if the sea is churned by the gathering storm, scattering bodies.
Authorities - wary of the anger among relatives about the time the search ios taking - have mobilised trawlers and installed 13-kilometre-long (eight-mile-long) nets anchored to the seabed across the Maenggol sea channel to prevent the dead being swept into the open ocean.
Dozens of other vessels and helicopters have been scouring the site and beyond, with the search operation expanded up to 60 kilometres from the scene of the disaster, while coastal areas and nearby islands, will also be searched.
Tyhe official probe has focused on a long delay by the ship's captain in issuing the evacuation order, as well as on the ferry's overloaded cargo and possible inaccuracies in the passenger headcount.
Prosecutors have raided a host of businesses affiliated with the ferry operator, the Chonghaejin Marine Company, as part of an overall probe into corrupt management.
The widening investigation has also seen travel bans put on eight current and former executives of the Korea Register of Shipping - the body responsible for issuing marine safety certificates.