Cairns coroner Kevin Priestly released his report into the death of Julian Wlodarczyk, 62, who died almost four years ago at the Daintree River Crossing, north of Port Douglas.

The incident happened just after midnight on April 30. Ferry master William Smith was about to leave when he saw a car flashing its headlights on the northern riverbank.

Thinking the driver might need help, Mr Smith took the ferry across the river to the car. He found Mr Wlodarczyk with the bonnet of his Toyota Camry raised.

"You would not believe the trouble I have had with this car," Mr Wlodarczyk said.

The car was then driven onto the middle of the ferry and Mr Smith started to return to the southern bank without a traffic controller, ropes or bollards, which were normally used to manage cars.

While the boat was still making the crossing, Mr Wlodarczyk's car suddenly began moving forward.

Mr Smith yelled through the PA system on the ferry, blasted the horn and began raising the ramp.

The car continued up and over the ramp and plunged into the river about 20 metres short of the south bank.

The ferry master saw the car sink and threw a life buoy into the water before calling for help.

The car was pulled from the river by a tow truck at least 90 minutes after it sank and Mr Wlodarczyk's body was found inside.

An autopsy conducted by Dr Paull Botterill concluded the cause of death was drowning due to multiple drug intoxication, including methamphetamine, diazepam, codeine and cannabis.

The coroner said Mr Wlodarczyk most likely died because he thought the ferry "had reached the southern bank". He also noted darkness and rain would have affected Mr Wlodarczyk's senses and the mixtures of drugs would have impaired him further.

However, Mr Priestly said "lessons should have been learnt" from two previous incidents.

The first incident occurred on November 20, 1998, when the car door Stephen Terry was opening was hit by a trailer of a moving truck, causing him to fall under its wheels. He died as a result.

Douglas Shire Council recommendations from the incident imposed a requirement for a system of ropes and bollards to control the loading and unloading of vehicles, but did not address potential vehicle containment problems.

Just more than two years later, Peter Mansfield drove through the rope barricade on the ferry and into the Daintree River about six metres from the shore ramp. He managed to escape his sinking car.

The circumstances surrounding the incident were very similar to those of Mr Wlodarczyk's death more than 12 years later.

Mr Mansfield's senses were impaired by rain and car headlights on the opposite bank, he felt the ferry stop and heard the ramp drop so drove off assuming the boat had reached the bank.

However, the ferry master later explained he couldn't see the southern bank so he stopped the boat and lowered the ramp to inch his way towards solid ground.

"This incident clearly demonstrates that there is a real risk of a driver making an error of judgement and driving off the ferry before it reached the bank," Mr Priestly said.

"If traffic management extended to include the concept of containment, the likely outcome would be a damaged vehicle, not a vehicle overboard."

Mr Priestly described these incidents as "missed opportunities".

"That incident (Mr Mansfield's accident) should have been investigated, lessons learnt (the need for containment) and those lessons should have informed marine safety officers throughout Queensland and prompted checks in like situations," he said.