The Virgo Transport 8 was carrying 243 people when it lost contact early Sunday while travelling from Surabaya in East Java to Banjarmasin in South Kalimantan.

Authorities have rescued 108 people from the vessel, according to Indonesia’s National Search and Rescue Agency.

Rescue teams, including the coast guard and navy, have been working in difficult conditions as strong winds and high waves make it harder to reach the vessel and search for those still missing.

The rescue agency said it had deployed at least 622 personnel, 17 ships, five helicopters and aircraft as part of the operation.

However, turbulent seas have prevented specialist underwater rescue teams from beginning a full search around the partially submerged ship.

Mohammad Syafii, head of Indonesia’s national rescue agency, said the conditions remained challenging and that authorities were identifying additional personnel with specialist skills while waiting for the weather to improve.

The ship was reportedly struck by waves reaching about three metres during the incident.

Another rescue official said the vessel leaned heavily to one side after strong waves hit its starboard side.

The capsized ship is located about 80 nautical miles, or nearly 150 kilometres, from the rescue command centre at Trisakti Port in Banjarmasin.

Rough weather has also made it difficult for rescue vessels to dock near the stricken ship.

As of Monday afternoon, none of the 129 missing people had been found, according to officials quoted by Reuters.

The search was continuing despite the difficult conditions.

Transport Minister Dudy Purwagandhi said the vessel had a capacity of about 500 passengers, indicating that it was not overloaded.

The exact cause of the accident remains under investigation.

The incident has raised renewed concerns about maritime safety in Indonesia, an archipelago of more than 17,000 islands where ferries and passenger ships are an important and affordable means of transportation.

The Java Sea has previously been the scene of major maritime disasters. In 1981, the Tampomas II sank in the region, killing nearly 600 people according to some estimates.

For families waiting for news of their relatives, the search remains an anxious race against time as rescuers continue efforts to reach those who may still be alive.