The drowning toll jumped 26 percent in 2015, bucking a steady downward trend over a number of years.
Preliminary figures released on today revealed 113 people drowned last year.
That was up from the 90 drownings in 2014 and also well above the five-year average of 103.
"After having the toll tracking steadily downwards for a number of years it's extremely frustrating to be announcing a significant jump in the number of drownings during 2015," said Water Safety New Zealand chief executive Matt Claridge.
Waikato has the highest toll with 18 deaths, followed by Auckland (16) and Northland (15). Canterbury's figures show its worst drowning toll since 1995, with 14 deaths, while Otago (5) and Southland (5) both reduce their tolls from 2014.
More than three-quarters of the deaths were classified as preventable, Water Safety said.
Just over 80 percent of the victims were men and Maori are again over represented in the figures with drownings up by 33 percent on 2014, at 24 deaths. Asian drownings are up from 11 in 2014 to 19 in 2015.
The biggest age group was the 15-24 year olds, with 24 deaths.
"We're extremely concerned by this, and with school pools continuing to close and swim and survival lessons becoming harder to access, the situation could get much worse," Mr Claridge said.
Water Safety says 2016's drowning toll now stands at 13 compared to 20 the same time last year.