Great Barrier Reef
The Great Barrier Reef was worth an estimated $4 billion a year in tourism revenue for the Australian economy before the coronavirus pandemic Photo: AFP / SARAH LAI

The tourism sector at Australia's famous Great Barrier Reef is under threat after the death of a second tourist while snorkelling in less than three weeks.

A 76-year-old woman, believed to be from Spain, was reportedly pulled from the water at Michaelmas Cay, a sand island 43km northeast of Cairns after she was found unresponsive before 2 pm on Tuesday.

During the incident, the woman was on an 80-person boat tour operated by Quicksilver Connections. Tour operator Quicksilver said lifeguards and an off-duty doctor, who was also on board, performed CPR but the woman could not be revived, according to reports in Australian media.

The woman had been swimming in front of lifeguards and was wearing a life jacket when the drowning occurred. She was part of a 25-person Spanish tour group who were among the 80 tourists travelling on Quicksilver Group's luxury 32m Ocean Spirit catamaran for the Michaelmas Cay day trip from Cairns.

"Our thoughts are with those affected by this incident and their families," Quicksilver Group managing director Tony Baker said in a statement.

"Our staff are trained to respond to medical incidents and we take the safety of our guests very seriously. We will assist the authorities in any way we can and work with them to ensure the safety of our region so visitors can continue to enjoy snorkelling activities," added Baker.

Quicksilver Group's managing director also confirmed the boat had returned to Cairns and counselling would be provided to staff.

The Queensland Police are currently investigating the case and are not treating the death as suspicious. It is also understood that investigators from the Workplace, Health and Safety firm will be helping police with inquiries.

According to the police statement, the woman's family have yet to be notified.

"Investigations are in the early stages and limited details are available at this time; however, police are not treating the death as suspicious. It may be some time before police can confirm the identity of the woman and notify their next of kin," read the police statement.

A Workplace Health and Safety Queensland spokesperson confirmed the government body was investigating the snorkelling incident and sent out a warning to all tourism operators to "exercise increased vigilance" amid the busy peak period.

This incident comes around two weeks after 71-year-old Adrian Meyer was swept away while he was on a Great Barrier Reef snorkelling tour near Norman Reef, about 60 kilometres north-east of Cairns. He hailed from South Australia.