Relatives of Dreamworld victims hold the Gold Coast theme park "totally responsible" for the tragedy.
The family of two of the four victims, Kate Goodchild and her brother Luke Dorsett, say they've been "throttled" by their deaths on the Thunder River Rapids ride in 2016.
"We are tired and devastated and horrified by the evidence that has come out this week," their father Shane Goodchild and Ms Goodchild's husband Dave Turner said in a statement released on Friday at the end of the first week of the inquest into their deaths.
"We hold Dreamworld totally responsible for this tragic event that could have so easily been avoided. It has throttled our family."
Cindy Low and Mr Dorsett's partner Roozi Araghi also died when their raft collided with another on the Thunder River Rapids ride in 2016.
Mr Turner and Mr Goodchild have attended all five days of the Southport Coroners Court inquest so far.
Ms Goodchild's mother Kim Dorsett and Ms Low's husband Matthew have also been in the gallery.
Dreamworld chief executive Craig Davidson said the park was "truly sorry" for the tragedy.
"We understand that this has been a harrowing week for them and that they are devastated and horrified," Mr Davidson said in a statement.
"We share those feelings. We are truly sorry this happened.
"It is our aim to assist the coroner as best we can to help understand how this tragedy occurred, and what we can do to ensure it never happens again."
The inquest heard Dreamworld sacked a ride attendant after a raft collision on the Thunder River Rapids ride almost two years before the fatal incident.
The families' barrister Steven Whybrow paraphrased a letter about the termination of the park employee after the incident in November 2014.
He said the ride operator shut down a water pump on the ride without knowing the location of all the rafts.
"A raft containing guests bottomed out at the top of the conveyor due to a lack of water supply," he said.
"An additional raft containing guests has then hit it and it has continued to be pushed by the conveyor until the conveyor was shut down."
No one was harmed in the 2014 incident.
Dreamworld employee Chloe Brix was questioned about the termination by Mr Whybrow, admitting she only knew it related to a "safety issue" due to "gossip" among staff.
A park engineer who serviced the 30-year-old attraction on the day of the tragedy revealed he did not know it was Dreamworld policy for a ride to be temporarily shut down after two malfunctions in a 24-hour period.
The company's breakdown policy stated an engineering supervisor needed to be informed and had to give authority to reset an attraction in that case.
The Thunder River Rapids ride's south water pump failed twice on the day of the tragedy before a third malfunction led to the fatal incident.
"Prior to that day I had a different understanding on how to proceed with a breakdown," engineer Matthew Robertson told the inquest.
Mr Robertson said on a shift as a park technician he could be called out to up to 20 "Code Sixes" (malfunctions) across the park's attractions.
The inquest resumes on Monday.
Australian Associated Press
