"While we understand why people want to cool off in the river on a hot day, this is another example of how the river can be very unforgiving."
The boy was not injured and was returned home by police.
Over thirty people have drowned since the beginning of December — seven more than the total for all of last summer, with another two months to go before the end of the summer reporting period.
Twenty people drowned in December 2021, more than double the figure for the previous December, when there were nine.
Water Safety New Zealand chief executive Daniel Gerrard said the uptick in fatalities was "unprecedented".
"This is the worst we've had the last six years."
The months-long lockdowns for Auckland, Northland and Waikato may have encouraged people to try things they hadn't done before, overestimate their fitness or delay the servicing of equipment.
• Be prepared – Check the weather forecast, marine conditions; know the local environment, safe swimming spots; set rules for safe play; use safe and well-maintained equipment.
• Look out for yourself and others - Always supervise children around water and keep children under 5 years within arm's reach; never swim alone. Swim between the flags at the beach and make sure everyone on board the boat is wearing a well-fitted lifejacket.
• Be aware of the dangers - The water will be cold. If it's a surf beach, it's a rip beach.
Know your limits. Challenge yourself within your abilities and skill level; know what you can and can't do in the water
