THE conveyor belt used to operate the Thunder River Rapids ride at Dreamworld - the scene of four deaths on Tuesday afternoon - is thought to have almost killed another visitor earlier this year.
The Courier-Mail reports a man in his 30s on the theme park's Log Ride was almost drowned after the belt slipped and trapped him.
The system and ride was investigated by Workplace Queensland and independent inspectors who later cleared the ride to reopen.
The Dreamworld website describes the Thunder River Rapids as being shut from Tuesday until Monday October 31 for "annual maintenance" following the fatalities.
The 34-year-old ride is open for children as young as two, given they have supervision.