The Virgo Transport 8 ferry was carrying 243 people, including 30 crew members and an unknown number of vehicles, when it capsized in bad weather early on September 13 during a voyage from Surabaya in East Java to Banjarmasin in South Kalimantan.
Indonesia relies on ferries to connect its 17,000 islands, with sea travel cheaper and more accessible than flying, but there have been numerous accidents.
Divers were navigating through unstable debris Hardiansyah Putra, a senior official from the country's search and rescue agency, said on Monday, adding that they would aim to find the missing passengers in the cabins.
The divers were limited to a maximum depth of 27 metres, he added.
From the Java Sea where the ship sank, rescuers were expected to airlift some recovered bodies using a helicopter on Monday, senior agency official I Putu Sudayana said on Sunday.
Dozens of divers swam through the 4277-tonne ship to find the missing people, trying to handle the unsound structures, the side to side tilting and the dangerously sharp objects scattered throughout the vessel, Putu said, adding that dense gas concentrations and leaking fuel posed further health hazards.
"Because of these reasons, the divers weren't able to get into the compartments," he said, adding that the ship's operator needs to right the ship and bring it to the surface.
The high-risk challenges facing the divers have slowed the progress of the search, adding to the anguish for distraught friends and family.
The death toll stands at 66 people, with 108 survivors and 69 still missing, agency figures show.
