Indonesian authorities say the Zahro Express ferry caught fire shortly after leaving Muara Angke port in north Jakarta, bound for Tidung island.
More than 20 people are believed to have been killed in the fire, with dozens more receiving treatment in hospital.
A search involving 10 ships has been launched in an attempt to find those still unaccounted for.
The majority on board are thought to be local tourists who were travelling to Tidung island to celebrate the new year with family and friends.
