Queenstown Lakes District Harbourmaster Marty Black said he had not seen similar conditions for more than 20 years. Although it might look like a great opportunity to strap on the skates, the ice could be hazardous.
"Kids like to go on the ice, but it gets dangerous when it starts to thaw out.
"Ice has affected some areas of our lakes and there are also frozen-over ponds around the district.
"We've had a number of reports of children and adults walking and playing on the ice."
He said while ice might look thick enough to hold plenty of weight, that might not be the reality.
Mr Black advised caution and asked parents not to let their children play near or on frozen waterways without supervision.
The great freeze has also caused a headache for commercial jet-boat operators.
Shotover Jet and Skippers Canyon Jet have both been off the water for eight successive days.
Shotover Jet operations manager Wayne Paton said yesterday the company had turned away 4000 customers, or about $500,000 in lost revenue.
"It's bad enough being off the water at all, let alone in the school holidays."
The jet-boats cannot run commercially because ice can get stuck in the jet unit of a boat, causing it to lose propulsion.
The water temperature was about 0degC, he said, but it was the overnight frosts of 10deg to 12deg that have left the rivers frozen.
Mr Paton said he had not witnessed similar conditions in the more than 10 years he had been with the company, but recalled a time in 1994, when the company closed jet-boat rides for 11 days straight.
"In 2007 we got quite bad out here, too, and there was the odd day we couldn't run, but not eight days straight.
Like Mr Black, Skippers Canyon Jet managing director Ben Hohneck said the company and district had not had "severe ice build up" since 1992.
Skippers Canyon Jet did not operate for 16 consecutive days in 1992 because of thick ice in the river, although the temperatures were much colder then, with frosts of 16deg.
The hardest frost this winter was 11.4deg last Monday.
However, consecutive frosts this year had not allowed the ice to break free and float downstream.
This had compounded the problem.
