Three Victorians and a South Australian woman have drowned in a deadly weekend on Australian waterways. 

A 17-year-old boy died near Mordialloc in Melbourne’s south on Monday afternoon, while another man aged in his 30s drowned at a lake in Ebden in the Victoria’s northeast earlier in the day. 

A 73-year-old South Australian woman could not be revived after she was pulled from the water at Seacliff, south of Adelaide, on Monday evening. 

The three Boxing Day deaths come after a 19-year-old St Albans man drowned on Christmas Day at Lorne in Victoria’s southwest. 

Both Victorian and SA police say they will prepare reports for the coroner. 

The deaths were a tragic reminder for people to stay vigilant around the water, Life Saving Victoria director Kane Treloar said.

“We understand that people want to come to the beach. It’s been a long time since we’ve had the opportunity to enjoy the waterways with our family,” he told reporters on Tuesday.

“We’re asking people to think about their safety because we want to make sure everyone’s coming home at the end of the day.”

There have been at least three other serious incidents across Victoria during the Christmas break, including one involving a toddler at Ocean Grove, Mr Treloar said.

He said the non-fatal drownings should not be discarded.

“These are instances where people are going to go to hospital and their lives are going to be changed forever,” Mr Treloar said.

“Their lives of their families are going to be changed forever, even though they have survived a traumatic event.”

Two Victorian children were rescued by police officers at St Kilda Beach in Melbourne’s southeast.

The girls, aged 10 and 11, were seen struggling in waters off the pier on Monday evening when the mounted branch officers came to their rescue. 

They were assessed by paramedics but did not need to go to hospital. 

Elsewhere, a young girl is being treated in a Sydney children’s hospital after being pulled from a pool in Wentworth Park on Monday evening.

And in South Australia, six stand-up paddle boarders were rescued after being swept out to sea at Moonta Bay on the Copper Coast on Monday night.

A passing boat saw them swimming with their boards about two kilometres offshore and picked them up.

One had ingested a large quantity of water and was taken to the Wallaroo Hospital for further treatment.

People should mindful of the potential dangers of using flotation devices, including stand-up paddle boards and inflatables in the ocean, SA Police said

“They are highly susceptible to winds and may be carried out to sea,” police said in a statement on Tuesday.