The ferry Sewol is on the sea floor and resting with its right side up, said Capt. Kim Jin-hwang, a South Korean navy officer commanding the rescue operation.
Searchers are now trying to reach a dormitory-style cabin where they believe as many as 50 girls may be, he said.
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Officials said conditions remained challenging inside the submerged vessel.
The visibility is very poor and lots of floating objects are blocking the way, the officials said. Some doors can't be opened because of the water pressure, and divers are having to break windows to gain access to certain parts of the ship.
Most of the bodies being found are wearing life vests, which probably made it harder for them to escape when the ship tilted because the exits would have been underwater below them. Divers have had to take life vests off the bodies to carry them out, Kim said.
Meanwhile, strong currents are pulling hoses supplying air to the divers, making it hard for them to stay underwater for long.
The divers have already searched all the easily accessible places, Kim said. They are expecting the search to become harder because of strengthening currents and harsher weather conditions