Shotover Jet, one of Queenstown's premier adventure tourism businesses, has been unable to operate for eight days because of ice in the Shotover River.
River operations manager Wayne Paton estimates the business owned by Ngai Tahu Tourism has lost about $500,000 because of the stoppage.
"Ice goes in the intake of the jets and it stops water getting in, so there is no propulsion," Mr Paton told NZ Newswire.
He said "the days have been beautiful", but the maximum daytime temperatures have not been high enough to melt the ice in the river.
Ice halted operations for 11 days in 1995 and it was an issue every winter, Mr Paton said.
Shotover Jet started operating on the upper Shotover River in 1970 and was one of Queenstown's first adventure activities. More than 3 million people have since taken the jet boat ride through narrow canyons.