Three teenagers have been rescued from the Kawerau River in Queenstown, a body of water which has grade 5 rapids.
The three males entered the river upstream of Rafters Road in Gibbston and immediately got into difficulty. Police were called to the area about 3.15pm.
Area prevention manager senior sergeant John Fookes said one managed to get himself safely onto rocks, but the other two in the group were swept a short distance down the river.
The second teenager was able to get to a bank on the opposite, inaccessible side of the river, while the third teenager was pulled out by a witness who jumped down a bank to render assistance.
Fookes said further down the river were the grade 5 Nevis Rapids which were incredibly unforgiving.
Due to the treacherous nature of the body of water, a rescue helicopter was dispatched and within half an hour was hovering by each of the three swimmers and rescuer so they could climb aboard to safety, he said.
Fookes said this was an incredibly close call for the young men, and it was extremely lucky someone saw what was happening and heard the screams for help.
Had the trio been swept any further downstream, emergency services would have been dealing with an entirely different scenario, he said.
He urged anyone swimming in rivers or exploring outdoors to do research first and treat the environment with respect.
Police wanted to thank all those involved in the rescue, and the people who were so quick to raise the alarm.