The ferry sank in bad weather in the Java sea off the northern coast of Central Java
province, but survivors have been found in waters up to 500km away.
Meanwhile, navy officials have said that the bodies of hundreds of people missing are probably trapped in the vessel.
"We presume hundreds of bodies remain trapped on board," Lieutenant-Colonel Tony Syaiful, a navy spokesman, said on Monday.
The authorities say they plan to locate and remove the bodies.
Nearly 250 people on board the vessel have been found alive, but about 400 remain missing. Ten bodies have been recovered.
A government transport investigator said last week that she suspected water entered the car deck, making the vessel heavy and unstable.