Investigators have removed the raft at the centre of the fatal ride, but Dreamworld remains closed - and a crime scene.Queensland Police assistant commissioner Brian Codd has told reporters the investigation into what caused four people to die will be thorough.
"We owe it to the deceased and their families, we owe it the community of Queensland, to get to the bottom of what caused this, to hold accountable any person that needs to be held accountable for this occurring if that is the case, but, most particularly, ensuring that this can never happen again."
Police say about 30 investigators are still at Dreamworld and will be examining footage of the deadly incident, the Thunder River Rapids Ride's maintenance log and the ride itself.
One of Australia's largest unions, the Australian Workers' Union, says it has been raising safety concerns about rides at Dreamworld since last April.
Queensland secretary Ben Swan says the union has been worried about many parts of the theme park.
"The union has been repeatedly making representations to Dreamworld about issues that our members have regarding the operation and maintenance of various equipment, including rides."
He has told SBS the AWU made a Right to Information request to park owner Ardent Leisure in April to be more transparent but it was refused.
"They have not been cooperative, as far as we are concerned, with respect to the issues the union has been raising on behalf of its membership. That is definitely our experience over the course of the last 18 months."
The AWU, which says it has a substantial number of workers employed at Dreamworld, says it will now form a detailed brief of its concerns.
Online, there has been an outpouring of grief for the dead and support for the families of the victims.
But there are also stories of repeated ride closures, safety issues and concerns about the theme park.
Dreamworld has now removed reviews from its Facebook page, but one from earlier this month (oct) raised serious safety concerns.
It is an unverified report, but a mother named Tracey Christensen posted to the page that there were maintenance or safety issues with The Claw, Wipeout and log rides.
"The kids get off The Claw and said one of their belt buckles came undone right up in the air. I told the attendants. They didn't listen."
She wrote that Dreamworld employees kept the rides going despite her concerns.
"All I want now is my money back, because having five rides with operational issues is not good enough. Someone will get seriously injured or killed one day."
In a statement to the stock exchange, Ardent Leisure said it is working closely with police to establish the facts of the incident.
It said the park was closed as mark of respect for the victims.
There have been a number of serious incidents at the 35-year-old amusement park.
In April, a man was pulled unconscious from the waters in the log ride after falling out and being run over by other boats.
In February, the BuzzSaw rollercoaster was closed for several days because of a safety issue.
Back in 2011, the same Bengal tiger bit two trainers within a few months.
In June of 2009, a helicopter crashed in the Dreamworld car park but there were no serious injuries.
And one of the park's most popular rides, the Giant Drop, had a gearbox problem in 2000 that left people stuck on it.
