A quick-thinking police officer is being praised for making a difference when he rushed to save a five-year-old boy from drowning.

He dragged the boy from the hot pools at Parakai Springs yesterday, and managed to revive him by the time a rescue helicopter arrived.

Westpac Helicopter paramedic Russell Clarke said his crew was expecting the worst when they arrived at Parakai Pools yesterday.

Luckily though, an off-duty cop had already revived the young boy.

"He was very calm and I'm sure he was aware that things could've been way different if he didn't notice the child floating face down and did something about," Clarke said.

Clarke said anyone who knows CPR and acts can prevent a tragedy, as seconds count in emergencies.