A U.S. snorkeller was left behind in shark-infested waters by a diving tour boat 30 miles off the coast of Australia.

Ian Cole, 28, had been diving in a reef called Michaelmas Cay off the north Queensland coast when he surfaced to find his boat had headed back to shore without him.

“I lifted my head up and I saw that the boat had gone – it had left me,” said Cole, who has been in Australia on a working holiday for about nine months.

In an incredible stroke of luck, he spotted another boat in the distance and was able to hail it.

Exhausted and close to drowning, he was plucked from the waters just in time.

The crew of the second boat radioed for the Passions of Paradise to come back and pick him up.

Now, Cole is now demanding a formal apology, saying he "can't walk away" without knowing tougher safety standards are put in place.

"All I was looking for was a formal, written apology and in writing an assurance of their procedure changes," he said.

"I couldn't walk away without knowing other tourists would be safe."

But Association of Marine Park Tourism Operators executive director Col McKenzie said standards were already strict enough.

"There's no legislating against stupidity," McKenzie said.

"Why is (Mr Cole) in the water 25 minutes after he was supposed to be back on the boat?"

Cole swam to another boat, about 30 metres away — but said he was panicking at the time and was very tired after spending two hours in the water.

"When that adrenalin hits you and you start to panic you lose your composure," he said.

McKenzie said an investigation had begun, but he admitted the staff member who conducted the headcount had broken the rules and had been sacked.

The incident had eerie echoes of the tragedy involving American tourists Tom and Eileen Lonergan, who were left behind by their dive boat off Port Douglas, Queensland, in January 1998.

They were believed to have been attacked and eaten by sharks in a horror that inspired the Hollywood film Open Water.

Following the Lonergans incident, regulations were introduced to ensure that the crews of vessels carried out a head count and each passenger's signature was recorded before any boat returned to shore.

But this was not done before the Passions of Paradise started on the return journey.

“They have had a staff member that has just simply broken the rules and that is what led to it,” McKenzie said.

The cost of Cole's trip has been refunded and he has been offered a restaurant voucher.

Two other Americans have been involved in a drama on the Great Barrier Reef that has attracted international attention.

Tina Watson, a 26-year-old from Alabama, died while on a scuba diving honeymoon in Queensland with her husband Gabe Watson in October 2003.

A dramatic photograph shows her lying on the sea bed after he claimed she got into difficulties. He was subsequently imprisoned in Queensland for her manslaughter.

On his release from jail and his return to the U.S. he faced what is an ongoing murder charge following demands by Miss Watson's family.