Fifth tourist in 3 months dies while snorkeling at Great Barrier Reef

(AP)

A British tourist has died on a trip to the Great Barrier Reef after swimming in an area suspected to be plagued by killer jellyfish.

The 63-year-old man, who has not been named, was killed during a snorkeling trip at Moore Reef-- 25 miles off the coastline of Cairns, in Queensland, Australia. He is believed to have been just feet away from the reef pontoon when he had a heart attack clinging to a safety ring.

A rescue helicopter was sent but emergency response crewmembers could not revive the man.

His death came the same day a 43-year-old woman was rushed to hospital by helicopter to Cairns Hospital in a critical condition after being pulled from the water off Green Island unconscious.

The incidents have heightened suspicions of attacks by Irukandji jellyfish in the area, one of the world’s most venomous creatures.

On Jan. 30, three children suffered suspected Irukandji stings off nearby Fitzroy Island, just under 20 miles from Moore Reef.

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Last month, several beaches in the area, including Three Cairns beach, were closed to the public following sightings of the jellyfish.

This is the fifth death in the last three months at the Great Barrier Reef.

In November, two French tourists died only minutes apart when they were snorkeling. Their deaths were followed by that of 60-year-old British scuba diver David Lowe from Sheffield, who was found on the ocean floor during a holiday with his wife.

At the time, cardiologist Dr. Ross Walker told ABC News, "I think it's highly likely they were stung by Irukandji. Irukandji are the size of your little fingernail, they're very small, you can't see them.

"Let's look at the fact and probability. It's highly unlikely that two people are going to die within minutes of each other just because they've got underlying medical conditions."

Professor Jamie Seymour said, "Because the water temperature has increased, it allows them to go further and further south."

This story originally appeared on The Sun.