An elderly Japanese woman has died while snorkelling at the Great Barrier Reef, in the fourth tourist death at the Australian attraction in a month.
The 75-year-old was pulled from the water on Tuesday at Moore Reef, about 45km (30 miles) from Cairns.
The woman, who had been snorkelling with a tour group, was given CPR but could not be revived.
Last month saw the deaths of two French tourists in their 70s and a 60-year-old British scuba diver.
The Australian Broadcasting Corporation said there were 10 deaths in total at the reef this year, double the marine tourism industry average.
It quoted the Association of Marine Park Tourism Operators as saying that most of the victims were elderly and had pre-existing medical conditions.
A spokesman said Wednesday they were considering regulation tweaks following the latest incident involving the Japanese woman, such as making visitors over a certain age acknowledge the risks associated with snorkelling and diving.
"While we are very proud of the fact we have the safest snorkelling in the world, we've got to sit down and have a really close look at all these events and see if there's anything we can do," Col McKenzie said.
The Great Barrier Reef is one of Australia's most popular tourist attractions, composed of thousands of individual reefs and hundreds of islands along the Queensland coast.
More than two million people visit it very year, generating more than A$2bn (£1.2bn, $1.5bn) in tourism revenues.