A father whose boat sank in Queenstown on New Year's Eve said he and the children aboard had ''less than a minute'' to abandon ship.
Mark Grieve, of Fernhill, said their experience served as a timely reminder to everyone on the water this summer.
Grieve was driving the 6m Hartley boat in Lake Wakatipu off Sunshine Bay about 7pm on Monday when it started taking on water.
He was with his 17-year-old daughter Payton and Ella Kersten, 9. They were towing Porsche Jarvis, 15, and Benjamin Baker, 12, on a double ski biscuit - a water sports inflatable on which people can sit.
''A section of the boat gave way underneath the motor,'' Grieve said.
''Everybody had life jackets. Another key factor was we had a flotation device [the biscuit] so we were all able to stay together in the water.
''We were in that water about 35 minutes. All the kids had wetsuits on because they'd been swimming, another key factor, so I was the only one that suffered from the cold. That lake is cold.''
The five were rescued by operators of the commercial jet-boat KJet, and a private boat, and taken to shore.
The lake, New Zealand's third-largest at 45.5km long, 11.6km across at its widest, and up to 300m deep, has a water temperature ranging from 8 to10degC. It has claimed many lives over the years.
''It was a reasonable amount of time to be in the water.
''So there's a lesson there - always be aware, wear life jackets, never be under-prepared. Particularly at this time of year, there's [a] lot of kids involved.''
Grieve said he was sure to always have an adult or older teenager on board with him, while he was driving the boat.
They had been at the lake about six hours with others, who were on shore.
After having a barbecue and swimming, they had been doing circuits towing the biscuit for about two hours.
Harbourmaster Marty Black said: ''It just shows you [how] easily things can happen and if you're not prepared for things going pear-shaped, we could have had fatalities.
''Fortunately, they all had life jackets on, the kids had wetsuits and life jackets on.
''But there's a warning. Just be careful out there. Check your equipment — obviously something went wrong with the boat. That's plan A.
"Plan B is what you do when something goes wrong. That's pretty important.''