Sixty-one people drowned in New Zealand during the first six months of this year, a 30 percent increase on last year.
Water Safety New Zealand says the preliminary six-monthly figures are the highest year to date toll, since 2011.
CEO Matt Claridge said the year got off to a poor start, with 21 deaths, and had not improved since.
"We're acutely aware that 61 families are mourning the loss of a loved one, in what are mainly preventable drownings. And we're only half way through the year."
Rivers claimed the most lives with 17 deaths occurring there - the highest number in five years.
Fifteen people died at beaches, up from just six at the same time last year and slightly above the five-year average.
Mr Claridge said while winter was not typically the time of year people visit the beach or river to swim, drowning is a year round issue.
"Everyone needs to think about keeping safe in, on and around the water all of the time. A significant number of drownings occur when the victim had no intention of being in the water, so it's hugely important to up-skill yourself with water safety knowledge and learn swim and survival skills regardless of your intentions."
Of the 61 victims, 15 were aged 15-24 and 50 (or 82% of victims) were male.
Matt Claridge said Wellington had had an especially bad start to the year with eight men drowning in the region, the highest number since mid-1993 and double the five year average.
Surf Life Saving New Zealand CEO Paul Dalton agreed that the high overall drowning statistics were alarming and said a common factor in beach drownings seemed to be unfamiliarity with an area.
"People need to take responsibility for their own safety in and around the water, especially when lifeguards aren't on patrol. It's important to understand what risks they may be putting themselves, or their children, into and take practical steps to avoid them; in particular asking for and listening to the advice of locals," he said.
So far this year swimming has claimed 11 lives. Underwater activities - such as free diving, snorkeling and scuba diving - resulted in five deaths.
A further 16 deaths occurred as a result of 'other events' such as motor vehicle accidents, suicides or homicides.