Research reveals that 60 per cent of children aged under 12 cannot swim 50 metres without assistance or stay afloat for two minutes, the yardstick used to determined standards.

High costs, transport issues and cultural barriers are the most common reasons for children failing to learn to swim properly.

With summer now in full swing and the school holidays just around the corner, Lifesaving Victoria has urged parents to ensure their young children learn these potentially life-saving skills.

Principal research association, Bernadette Matthews said the figures were a lot worse than she had imagined.

"It does concern us that there has been a reduction in the swimming capabilities of children in Victoria," she said. "We believecompeting demands of the school curriculum have played a role in this."

The shocking statistics means Victoria has one of the worst children swimming rates in the country: Royal Life Saving Society Australia research indicated that one in five children could not swim to minimum standards.

A Department of Education and Early Childhood Development spokesman said swimming lessons had been an "essential" part of the school curriculum since 2005.

"Water safety is included throughout the years of schooling, from prep where students practice moving safely around water to the development of swimming stroke techniques and proficiency in a range of water safety skills in secondary school," he said.

Most children learn to swim through their schools but parents are increasingly reaching out to private swim schools  to complete their children's aquatic education.

Swim Australia runs more than 100 private swim schools across Victoria. Chief executive Ross Gage said children from migrant families were more likely to have poor swimming skills and extra effort was needed to ensure they had access to affordable swimming lessons.

"They come to Australia and where they come from doesn't place as high a value on swimming as we do here."

Lifesaving Victoria reports that drowning is the most common cause of death for children aged between 0-14. In the year ending June 30, 10 children aged between five and 14 drowned across Australia. That number is down 29 per cent historically on the 10-year average.

Mr Gage said there was a real concern children with poor swimming skills will be at higher risk of drowning or injury as they get older.

As the school holidays get under way, Ms Matthews urged parents to keep a close eye on their children when they are in the water, whether they are strong swimmers or not.

"We certainly think there is the potential, if kids don't learn these skills at an early age, that we will see more drownings in the future.

"The most important thing for parents is supervision. Kids under five need to be in arm's reach at all times. Children under 10 should be within your sight at all times," she said.