Nearly 80 people are still missing after the ferry ran into trouble in rough weather in Sulawesi on Saturday, but search and rescue teams returned to the seas at daybreak on Monday in an increasingly desperate bid to find any sign of the boat and its passengers.
Three people, including two children, have been confirmed dead so far.
All the victims are Indonesians.
Officials say 39 others have been plucked from the water alive, some by fishermen after desperately clinging to buoys and fishing traps for hours in huge swells until help arrived.
The families of those missing have been nervously awaiting any news of their loved ones in Siwa, where the ferry had been destined before it sent out a distress signal and lost contact with authorities.
But after days of torrid weather in the Bay of Bone where the ferry disappeared -- including waves up to five metes (16 feet) high -- authorities are hoping calmer conditions will aid the search.