Four people, including New Zealander Cindy Low, died when the Thunder River Rapids ride flipped at the theme park on the Gold Coast, in Queensland on October 25.
Queensland Police said post mortem examinations had been completed and the bodies released to their families.
They said police would advise when the investigation at Dreamworld was completed, but it was "anticipated this may take some time".
Two children on the raft were thrown from the ride, but the four others did not survive.
A memorial day was originally planned, with entry costs to be donated to the Red Cross. But Dreamworld later released a statement cancelling the public event.
The tragedy sparked a month-long safety crackdown across Queensland's theme parks.
Dreamworld remains closed as police continue to investigate the accident site, and it has been announced that a permanent memorial will be established within the park.
The park will remain closed to the public until at least the completion of the funerals of the four victims.
