Four people were rescued from Lake Rotorua, close to Mokoia Island, after a boat capsized.
They were treated by St John Ambulance with one taken to Rotorua Hospital with moderate hypothermia.
A police spokeswoman said it was a joint rescue mission between the Coastguard Rotorua Lakes and the police.
Coastguard Rotorua Lakes president Barry Grouby said the five sail boats were taking part in a race organised by the Rotorua Yacht Club.
Mr Grouby said the conditions had caught the sailors out, with the weather changing quickly to blustery winds.
"Rotorua Lakes coastguard were fantastic at rescuing them and bringing them in," he said.
Mr Grouby said those rescued were experienced sailors and had been wearing life jackets.
Rotorua Yacht Club commadore Robin Parr said it was a yearly race around Mokoia Island and back.
"We thought it would be a fairly quick race."
Mr Parr said he was thankful to the Coastguard for their help.
He said three of the boats had been left behind the island and would be picked up when the wind died down.