Authorities have been scrambling to locate all 65 people on board the ferry, including 53 passengers and 12 crew members, after the vessel sank less than half an hour after departing from Banyuwangi regency’s Ketapang Port in East Java to Bali's Gilimanuk Port late on Wednesday night.

As of Sunday, a total of 37 passengers of the ferry had been located, consisting of 30 survivors and seven fatalities, while the 28 other passengers remained missing.

Coordinator of the rescue mission and the National Search and Rescue Agency’s (Basarnas) deputy for operations, Rear Adm. Ribut Eko Suyatno, told reporters on Sunday that there is a possibility that the bodies of the remaining passengers are trapped inside the wreckage of the ferry underwater.

“That’s a possibility that [we strongly] suspect. But I can not confirm it until an underwater observation using a remotely operated vehicle [ROV] and a direct inspection by divers have been conducted,” he said.

The Navy’s KRI Fanildo-732, a minesweeper vessel equipped with sonar technology, previously detected what is believed to be the wreckage of the ferry on Saturday, about 800 meters from the presumed sinking point, at a depth of around 50 m.

Ribut said the Navy was still analyzing raw data from the underwater scans, after which the search team would determine how and when to deploy the divers.