The room was meant to accomodate 38 people.
According to a South Korean Navy officer, the group was crammed into a dormitory and all were wearing lifejackets, BBC reported.
Some 183 bodies have been recovered from the Sewol so far, but scores of people are still missing, presumed drowned.
The head of the operation to retrieve bodies said Friday he had "no idea" how long the search would take.
There were 476 people on board, with many trapped inside as the ferry listed and sank within two hours of distress signals being sent. A total of 174 passengers were rescued.
Many of those who died or are presumed dead were students and teachers from Danwon high school, south of Seoul.