More than 190 people are now believed to be missing after Monday's ferry disaster on Lake Toba, on the Indonesian island of Sumatra, police said on Wednesday.
The number, revised up from 130, is three times the number of passengers the ferry was licensed to carry.
Lake Toba, the world's largest volcanic lake, was busy with tourists celebrating the annual Eid holiday when the ferry sank in poor weather.
Many victims are thought to have been trapped inside the vessel, police said.
Indonesia's national search and rescue agency said only 18 survivors had been found, all within hours of the tragedy. Three bodies have been recovered, a BBC report said.
Authorities say the boat operators didn't hand out tickets so there are no records of who was on board.
Desperate families have spent the past days desperately waiting for news and hoping that the search and rescue boats returning to shore might bring any news.
On Wednesday, divers and an underwater drone joined the search efforts. The teams still need to locate the wooden ferry at the bottom of the 1,500-ft-deep lake.
"This is a test from God for our family," Fajar Alamsyah Putra told BBC News Indonesian. His brother Bagas Prama Ananta, is among the missing passengers.
He had been spending the holiday on Samosir, the large island in the middle of the lake.
"Only God knows if he is safe or not," said Fajar Alamsyah Putra.
"He was inside the ferry when the ship sank and could not get out, the ferry quickly capsized. A friend of his was on the deck and was able to jump off in time to get help from another passing ferry."
Yanti Samsudin said her brother was also on the boat. "I still hold out hope that he will be found alive, if not then I hope his body will at least be returned to us."
The head of the local disaster mitigation agency, Riadil Lubis, said they were doing their best to keep the families updated.
"We have set up an information centre with boards with lists of the survivors, the missing and the confirmed dead. It's crowded with people."
According to official regulations, all boats in Indonesia must not exceed capacity and must have life jackets for every single passenger on board.
But authorities admit that they struggle to monitor all the boats operating across Indonesia's vast archipelago.
The national committee for transportation safety says that 40 percent of boat accidents in Indonesia are caused by human error, and only 12 percent are due to bad weather.