There were 12 drowning deaths in April, contributing to the worst start to a year in the water since 1997.
There have already been 57 drowning deaths since January, well above the average of 43 over the last five years.
However, 16 of the deaths are classified in the "other" category, with 12 suicides and four road accidents where drowning was the cause of death, compared with an average of six in this category over the previous five years.
There have been 27 recreational and 12 non-recreational drownings since January, which is roughly consistent with the average for the last five years, according to Water Safety New Zealand.
Major contributors to the recreational toll have been swimming (10 deaths), recreational boating (six), underwater diving or snorkelling (five) and angling (three).
Eleven accidental immersions have also blighted the start of the 2011, including six cases where unsupervised young children gained access to water without an adult being aware.
Water Safety New Zealand executive director Alan Muir said the number of deaths was not acceptable, particularly when it came to the recreational drownings.
"Invariably, the actions of the victims have contributed to their own demise in these incidents. Whether it is by ignoring the most obvious of safety considerations or not recognising their own limitations, many in this group made a poor decision that cost them their lives."
Males have accounted for 79 per cent of the year's drowning deaths.