An inquest into the ride malfunction that killed four at the Dreamworld theme park in Australia is underway, with a Queensland court hearing there had been "a number" of previous incidents on the ride.

The tragedy, which happened in October 2016, occured when two rafts on the park’s Thunder River rapids ride collided, killing Cindy Low, Kate Goodchild, Luke Dorsett and Roozi Araghi.

A review, conducted by Workplace Health and Safety Queensland (WHSQ) last year, outlined a number of ongoing public safety issues, namely the lack of training or qualifications for ride operators.

The state of Queensland started its long-awaited inquest into the deaths today (18 June). The inquest heard that the ride had broken down at least three times previously, also malfunctioning two times in the hours leading up to the accident.

During the inquest, it was said that the ride's operators were unaware of an emergency stop button, which would have shut the ride down in two seconds. The inquest was also told that staff had previously raised concerns about safety in 2001 following a similar raft flipping incident. The theme park was also given a low safety rating during a 2016 audit.

Speaking during the inquest, detective sergeant Nicole Brown said that a water pump had failed three times on the day of the accident. It was reset twice but the third failure resulted in the collision of the two rafts. Two children were also in the raft, but were ejected and survived.

The inquest will take two weeks to complete. 37 witnesses are scheduled to appear, testifying on the ride, its history, staff and whether or not the accident could have been avoided.

The ride itself has since been demolished by DreamWorld's operator, Ardent Leisure. Following the deaths, the state introduced new industrial manslaughter laws, with safety around theme park rides also tightened.