Baby boomers taking up water sports in their retirement have driven up the number of Australian drownings.
And child drownings nearly doubled last year, with 10 more deaths in the under-four age bracket.
The Royal Life Saving Society's annual report says of the 291 drowning deaths last year, 114 were over-55s.
The figure is the highest in 10 years for the age group, which now accounts for more than a third of the total.
The growing number of retiring baby boomers, many of whom take up water-based hobbies, could be to blame for the increase, Royal Life Saving Society chief executive Justin Scarr said.
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"We're finding our parents and grandparents are boating and fishing their way into retirement," he said.
Accidents involving watercraft were responsible for 27 drowning deaths in people over 55 years old.
Existing medical conditions, such as heart problems, as well as medications which affect balance, could pose a threat for over-55s when out on the water, he said.
Of child drownings, 81 per cent of all deaths occurred after a child was left unsupervised.
Men also continued to make up the vast majority of deaths, accounting for 82 per cent of all drownings.
Thrill-seeking behaviour and alcohol were major factors, Mr Scarr said.
"We're calling on fathers, brothers and mates to look after each other and point out silly and foolish behaviour around water," he said.
The results reverse the previous year's downward trend, which saw total deaths drop to 284.
