An emergency training exercise in Sydney's Botany Bay ended with real casualties when volunteers needed medical attention after awaiting "rescue" in chilly waters.
Exercise Splash on Saturday was designed to test rescuers' ability to save lives if a plane from nearby Sydney Airport should ever ditch into waters off Port Botany.
But 12 of the surf life-saver volunteers who had been pretending to be aircraft passengers stranded in the water were treated for hypothermia and sea-sickness.
"Twelve people were assessed by ambulance officers for hypothermia," a New South Wales police spokesman said Sunday, adding that five were taken to hospital.
One volunteer said he was supposed to be swimming in the water but after he had been in the sea for a while decided to make for a lifecraft.
"I was one of the swimmers, we were huddled up in a bunch and got in a lifecraft and the wind chill was just, yeah, it's been very cold," he told the Seven Network.
But officials said the operation, which was designed for poor conditions, was necessary and good planning ensured that those suffering from the cold received treatment quickly.
"This is the plan you'll see swing into action if a jumbo goes down at Sydney Airport," Police Minister Michael Daley said.
"Just last year, when a plane ditched into the Hudson River in New York, we saw how important this preparation and training can be."