A British tourist has died while on a dive trip with his wife at the Great Barrier Reef, two days after two French tourists died while snorkelling in the region.
The 60-year-old Englishman was on his second certified scuba dive of the day at Agincourt Reef, off Port Douglas, when another diver spotted him on the ocean floor with his regulator out of his mouth.
He was taken back to the boat, the Silver Sonic, owned by operator Quicksilver, where he was given CPR as it raced back to the Quicksilver helicopter pad.
They were met there by a doctor who also performed CPR on the man, but he couldn't be revived.
Col McKenzie, from the Association of Marine Park Tourism Operators, said the man was an experienced diver and accompanied by his wife on the dive boat, which could hold up to 80 people.
The incident continues a horror month for Queensland tourism with four people dying on a ride at Gold Coast theme park Dreamworld three weeks ago and now three on the Great Barrier Reef.
Mr McKenzie said the case was in contrast to that on Wednesday which claimed the lives of French tourists Jacques Goron, 76, and Danielle Franck, 74, while snorkelling on Michaelmas Cay, north of Cairns.
"The one on Wednesday was two people in their mid-70s who were very unhealthy," Mr MacKenzie told AAP.
"In this instance, we've got a qualified diver who was diving in very safe, clear, warm water, and we have no idea what's caused the issue."
Mr MacKenzie said he welcomed the investigation into the deaths, but is worried about the negative attention generated by the incidents.
"What concerns me is the crazies out there, I mean we've already got people saying we should close down the marine tourism industry because we've had three fatalities in a week," he said.
"I'm not saying we haven't got room to learn, to do something a little bit different, but we're very proactive about looking after the safety of our people."
Police and workplace health and safety are investigating the 60-year-old's death.
