Friends Jake Demmery, Matt Stark and Brad Robinson were fishing close by when they heard the teenager's desperate call for help about 2.15pm on Tuesday.

Without any regard for their own safety, two of the rescuers jumped into the popular swimming hole to help Port Macquarie teenager Ryan Collins, while the other helped to pull him from the water.

Meanwhile Ryan's mate Grant Barnes called Ryan's father George at the Highway Service Centre, sparking the rescue mission.

The impact of the 20m jump left the 19-year-old with a badly fractured leg.

He was winched to safety by the Westpac Rescue Helicopter and flown to Port Macquarie Base Hospital, where he remained in a stable condition yesterday.

Lifeguards have issued a stern warning to adrenaline seekers after the accident.

Hastings Council senior lifeguard Jamie Martin said there were many risks involved when embarking on a vertical drop such as the blowhole.

"It is clearly a risky activity in a very risky area," he said.

Mr Martin said the impact of hitting the water or misjudging the drop and hitting a rock could result in serious injury.

Even if a swimmer landed successfully in the blowhole, the waves caused a surging effect which could force swimmers into a cave.

Mr Martin emphasised the need to swim at patrolled beaches.

"It's a little frustrating," he said.

"The community has rallied like nothing I've ever seen before raising thousands of dollars to build surveillance towers on five of our major patrolled beaches, yet we are still seeing accidents on beaches that are unpatrolled.

"Let's keep our beaches fatality free this year and always swim between the flags."