The second stingray attack in four months at Akitio Beach, southeast of Dannevirke, saw a 19-year-old airlifted to Palmerston North Hospital for treatment.
The stingray's barb pierced Morgan Robinson's buttock from one side to the other.
"Thankfully, the barb remained attached to the stingray," said Jeff Bryan, Akitio Volunteer Fire Brigade member.
"But their tails are covered in nasty germs and leave a lot of infectious stuff inside. It was important to get the wound clean as soon as possible."
Mr Robinson was on the reef with his uncle last month, checking nets set by his family, when he stood on one stingray and was stung by another.
A resident called 111 and two fire appliances, two ambulances and the Palmerston North Rescue helicopter attended the call.
The helicopter landed in the front paddock of Moanaroa Station, where Mr Robinson was loaded on board.
"Morgan was in a bad way, but holidaying nurses applied frozen peas to the area to help with the pain and reduce the swelling," Mr Bryan said.
"It's put an end to his holiday, that's for sure."
Mr Bryan said Mr Robinson was given antibiotics to ward off infection and is making a full recovery.
He said stingray numbers were on the increase at Akitio Beach, and warned people to be aware while setting nets or pots on the reef.
"Take a stick and use it to ward off stingrays," Mr Bryan advised.
"People used to take sacks out and slap the water with them to scare stingrays off. Use a stick in murky water, or to poke them out of the way."
In October, a diver was airlifted to hospital after being stung in the foot at Akitio beach but was back in the water the following day.