Queenstown's harbourmaster is warning people that emergency flares should not be set off for fun because the searches they trigger cost a lot of money.
A fruitless two-hour search of Lake Wakatipu on Thursday after the sighting of a flare cost thousands, harbourmaster Marty Black says.
Two boats and a helicopter searched the lake for several hours after a red distress flare was spotted by a member of the public.
"People might not realise the knock-on effects of what might seem like a bit of fun letting off a flare," Mr Black said.
"The coastguard and a helicopter pilot were out for almost two hours, searching for a boat in trouble on the lake in the middle of the night. That's a big ask of volunteers who have already done a full days work and have to be up again in the morning."
The cost of the helicopter search would have been more $4000, Mr Black said.