Three families were grieving last night after a horror day on the water brought three separate drownings.
A male swimmer in his 50s died after suffering a heart attack while competing in the 2.5km Taupo Epic open water swim yesterday.
Organisers said the swimmer got into difficulty and attempts to resuscitate him by the water safety team and St John paramedics were unsuccessful.
In Tauranga, a fishing trip turned to tragedy yesterday after a 51-year-old Aucklander drowned while setting flounder nets in an estuary.
The man and a 49-year-old friend from Tauranga had been wading in thigh-deep water, setting out flounder nets near Tye Park, Welcome Bay, about 1.30pm.
The 49-year-old man is in Tauranga hospital. His condition was described as serious.
And a man was missing, presumed drowned, after being caught in a rip while swimming with friends in Titahi Bay, near Wellington.
The Westpac rescue helicopter, Mana Coastguard and the Titahi Bay Surf Lifesaving Club were combing the area for signs of the missing man last night.
Water Safety New Zealand boss Matt Claridge said he was particularly concerned at the number of swimmers who had drowned in open water events in recent years.
"We will be investigating this Taupo death very closely."
However, Swimming New Zealand chief executive Mike Byrne said there was a strong safety protocol in place at the event and the team responded appropriately.
About 500 swimmers competed in the day's events, which included races for Olympic through to recreational swimmers, in cool and choppy conditions on Lake Taupo.
Nine people lost their lives to drowning in New Zealand waters during the official holiday period - between Christmas Eve and January 5.
Claridge said Kiwis were heading to the water in greater numbers because of the hot weather and warned them to be extra cautious on the water.
"People are trying to make the most of their holidays and the warm temperatures and get out on the water, but they need to be reminded just how dangerous it can be."By Joanne Carroll Email Joanne