In a split second, Daniel Thompson faced a parent's nightmare.
His son Will, 3, was just metres away when he wandered too close to the backyard pool, slipped and the water closed over his head.
But Will's swimming training kicked in. He pumped his little legs and pulled himself to the edge where his anxious dad scooped him up.
Mr Thompson says it showed the value of Will's swimming lessons from the age of four months.
They were inside the pool fence when Mr Thompson was cleaning the pool and, in a moment's distraction, Will was gone.
"I was shocked," Mr Thompson said. "It wasn't something I was expecting. He's been in the pool area with me before."
Mr Thompson believes that without Will's swimming lessons and if he had been a little further away, Will would have sunk to the bottom.
"It highlights the importance of lessons," he said.
Swim Australia chief executive Ross Gage said it was increasingly common for parents to familiarise their children with pools and water at a young age. "Will could have drowned very, very, easily," he said.
"A parent might think 'I'm only a few metres away', but if they have their back turned they don't hear a sound. The child just slips in.
"They drown without a sound."
He urged parents to be hyper-aware this summer of water safety.He said Australians were surrounded by water - pools, lakes, dams, beaches - as part of a great lifestyle but with the potential to create terrible tragedy.