Tragic coincidence: Tourism boss denies jellyfish killed two French tourists

A Cairns tourist operator has poured cold water on the theory that highly venomous jellyfish were responsible for the deaths of two French tourists at the Great Barrier Reef on Wednesday.

The pair's death has been attributed to heart attacks with a tour operator saying both had declared pre-existing conditions and had swallowed a lot of seawater.

Previously, Sydney cardiologist Ross Walker told News Corp their deaths were most likely from the Irukandji jellyfish.

“Two divers were affected by swallowing seawater? Give me a break,” he told reporters.

“Look at the facts here. You have jellyfish infested water, and the bite of the jellyfish stimulates a heart attack. I think they were more likely all bitten by Irukandji jellyfish.

“But if that gets out, then the people running the dive programs won’t get anyone in the water.”

However, that theory has now been heavily disputed by Passions of Paradise managing director Alan Wallish, who maintains it was nothing more than a tragic coincidence.

“We don’t get Irukandjis at this time of year and the two parties were very separate,” he said.

“The lady was 15 metres away from the boat ... (and) had a full stinger suit on.

“I really can’t see how jellyfish or stingers would have contributed in any way.”

The incidents happened in shallow waters at Michaelmas Cay about 11am as part of a catamaran activity, where 21 elderly French tourists were on board.

“The Passions of Paradise lookout on the beach noticed a man floating in the water and pulled him to the sand cay where he performed CPR. He was then assisted by a doctor on the sand cay," Chief Executive Officer Scotty Garden confirmed in a statement.

“The Passions of Paradise lookout on the boat saw a woman floating in the water and pulled her on to the catamaran where CPR was performed.”

The thumb-sized stingers are found in tropical waters, usually between October through to May.

They are the smallest and most venomous box jellyfish in the world.

Dr Sen Gupta from the James Cook University was also divided by their cause of deaths, telling the Cairns Post the chance of two people having heart attacks in the same place at the same time without being caused by an external factor was, “one in a million”.

“I would think there may have been something in the water, some toxin, maybe an envenomation," Gupta said.

“I think you would have to look at that.”