Since the start of summer on December 1 there have been 20 drowning deaths at coastal waterways, four more than the same time last year and already higher than the 10-year average of 16.

The toll does not include the death of a two-year-old girl who drowned in a park pond in Melbourne in the lead-up to Christmas and a three-year-old at Lake Macquarie on Christmas day.

Surf Life Saving Australia CEO Adam Weir said people should take simple precautions like swimming at patrolled beaches, wearing a life jacket when rock fishing or boating and always supervising children on, in and around water.

Sport Minister Richard Colbeck issued an urgent reminder to Australians not to become complacent after the recent string of drowning tragedies.

He said the incidents were an important reminder to look out for loved ones, read safety signs, swim between the flags and follow advice from lifesavers.

"A tragedy can unfold in seconds," he said.

"Can I urge Australians everywhere - families on holiday or mates catching up after a challenging period - don't be ignorant to the dangers."

Australian Associated Press