The confirmed death toll in South Korea's ferry disaster has crossed 100, but almost twice that number remained unaccounted for nearly a week into the rescue and recovery effort.

The official toll provided by the coastguard stood at 104, with 198 still missing. The 6,825-tonne Sewol was carrying 476 people - most of them schoolchildren - when it capsized and sank last Wednesday.

Some 174 people, including the captain and most of his crew, were rescued.

The expected final death toll of around 300 would make this one of South Korea's worst peacetime disasters.

Rescuers were still battling high waves to recover the bodies on board the submerged Sewol ferry.

The coastguard said more than 500 divers, 169 vessels and 29 aircraft are now involved in the rescue operation near Jindo Island.

However, the missions to find survivors in the wreckage, hampered by bad weather, murky waters and strong currents, have all ended in failure so far.

"We need cranes to come in and lift the vessel so that the water depth decreases. Then rescue efforts can pick up speed. But at a depth of 30-45 meters, even if there were survivors, it would be difficult to bring them up," said Hwang Jang-Bok, a volunteering civilian diver who arrived in Jindo soon upon hearing news of the accident.

Hwang added that the underwater rescuers could be swept away 50 meters downstream by the currents in an instant.

In addition to the physical challenges, a mental toll weighs on the divers heavily as well.

"Even if we were under physical stress, we wouldn't be able to feel it. We haven't rested in days. We work throughout the night. We eat one meal a day. But, I can't even fathom what the families are going through," said Choung Dong-Nam, head of a civilian diving team at the site.

PHOTO CAPTION

Searchers and divers look for people believed to have been trapped in the sunken 6,852-ton ferry Sewol near the buoys which were installed to mark the vessel in the water off the southern coast near Jindo, south of Seoul, South Korea, Tuesday, April 22, 2014.

Aljazeera