Firefighters found the remains after they gained access to the vessel for the first time, having extinguished a fire that had hampered search and rescue efforts since Wednesday night.
Responders in protective suits were seen carrying black body bags from a small boat onto a Coast Guard vessel, video footage released by the Coast Guard showed.
Thick smoke and extreme heat had earlier prevented rescuers from entering the ferry, which was carrying more than 130 people when it was engulfed in flames.
As families waited for news of missing relatives, some expressed frustration at the lack of information they were receiving.
It was not immediately clear how many people remained unaccounted for, but authorities had reported 84 missing before Friday's recovery of 30 bodies. The number of rescued stood at 43 as of Friday morning.
