Twenty-four surviving passengers were admitted to hospital but dozens are believed still missing, said the local disaster agency.
The packed traditional wooden boat left Makassar, provincial capital of South Sulawesi in the afternoon for a short journey to the resort island of Barrang Lompo, some 15 kilometres northwest of the city's coast. The boat reportedly hit a large wave amid bad weather and capsized.
Makassar police said the boat was overloaded. The cause of the incident is still being investigated.
According to statistics, almost 32 million Indonesians are on the move this week in the annual Eid Al-Fitr exodus. It was the latest deadly maritime accident in Indonesia, which relies heavily on boats to carry people around its 17,000 islands but has a patchy safety record.
On New Year's Day, nine people died after a passenger boat capsized when travelling from the city of Tarakan to Tanjung Selor on Borneo island.-VNA