Teenager on Dreamworld log ride suffered serious injuries after two boats went over him

A teenager who is still recovering from his injuries after falling from Dreamworld's log ride in April is "really distressed" by yesterday's horrific accident in which four people died.

Samson Sherrin, 19, was run over by two other boats as he lay unconscious in the water, suffering hip, rib and ankle fractures, neck and head injuries and acute respiratory failure, and nearly drowning.

The theme park visitor, from Brisbane, also caught pneumonia and has struggled with psychological problems and is still receiving counselling.

"His friend had to finish the ride, run all the way around and get him out," his lawyer, Sugath Wijedoru from Littles, told news.com.au. "Staff didn't get him out.

"He's been knocked unconscious... his clothes were torn. He's suffered a lower back injury, a groin injury because it kind of gouged him around that area.

"Obviously he's suffered psychological trauma. His injuries haven't stabilised."

News of the four tragic deaths on the Thunder River Rapids yesterday has left him "really distressed, really quite upset," added his lawyer.

Mr Sherrin has brought a public liability claim against the Gold Coast theme park, which is currently going through Queensland's pre-court processes of exchanging documents. He is alleging negligence by the park, owned by Ardent Leisure.

The Rocky Hollow Log Ride was closed after the accident but was given the all clear by Worksafe Queensland inspectors and reopened two days later.

Dreamworld chief executive Craig Davidson said at the time there had never been another incident of the same nature on the ride during the 34 years it had been operating and that guest safety remained Dreamworld's number one priority.

Park visitors said there had been problems on Thunder River Rapids earlier yesterday, before the deaths, and engineers were called in. Witnesses said they were stuck there for around half an hour while engineers drained the ride and filled it back up.

Social media users expressed concerns about ageing equipment and operational issues after the horror accident, with some claiming seatbelts had previously come undone on rides.

Australian Workers' Union Queensland secretary Ben Swan told ABC radio this morning: "We raised concerns directly with the company as far back as April 2015. We have had concerns about maintenance and operation regimes.

"I can't speak to the particular ride in question. What I can say is it is now a matter of public record because we put a right to information request into the Commission of Workplace Health and Safety that we have concerns.

"We've expressed those concerns directly to the company. I don't want to inflame the situation because I think people's priority should rightly be on taking care of the situation that immediately exists but we did hold some very grave concerns about safety of equipment and the operation of equipment at that site."

The cause of the accident remains unknown and Dreamworld management said they are "deeply shocked and saddened" by the deaths.