The police will today begin an investigation into the circumstances of yesterday's boating tragedy in Otago, in which one child died, and another remains in intensive care.
Emergency services were called out to Taieri Mouth, south of Dunedin.
The small boat, which had an outboard motor, flipped as it was heading out while those on board tried to cross the bar at about 1pm.
Five people were taken to Dunedin Hospital, but two adults and another child have since been released.
Police announced late last night that one of the children had died. Another child is now in a stable condition in the intensive care unit.
The group was rescued by local jet skiers and surfers, including two doctors who provided first aid.
Police have thanked those who helped out "and acknowledge the distress they may be feeling".
Maritime NZ have started an investigation and police will also investigate the case on behalf of the Coroner.
The boat has now been located.
Police said they were focused on supporting the family involved in the "tragic incident".
Sandbars: 'most dangerous' thing in our waters
Boaties are being told the tragedy is a reminder not to under-estimate the danger of sandbars.
Coastguard head of operations Rob McCaw said sandbars were a common feature of rivers and harbours in New Zealand, and are dangerous because of the dynamic combination of sand and silt deposits.
"You get a period of rough weather come through, or even just the standard in and out of the tide... it can change the characteristics of a bar and change the way the water's going to react around it at different heights of tide.
"So one of the biggest risks of bars is they are ever-changing, and you have to be really careful when you're using them."
Anyone heading for the open sea would likely have to cross a bar, but "there's nothing more dangerous", the Coastguard website said.
The risks were so high that the organisation provides a safety watch service they want boaties to use for every bar crossing. Those about to cross, make a Bar Crossing Report on Coastguard Radio, then signal they have safely crossed, afterwards. The initial report generates a search and rescue watch alert, and if the second 'safe' report isn't received, a search is initiated.
McCaw said it was important to do some groundwork before making a crossing,
"The biggest thing for getting across a bar safely is to actually take the time to go down and look at the conditions, have a look at the bar itself, talk to some of the locals who've just come in or about to head out, and just understand how the water in that particular patch works."
He said in particular, the two to three hours leading up to low tide is the most dangerous time to cross a bar.
Coastguard provides a safety checklist, and instructional videos for different bars around the country.