Boy rescued after falling off NSW blowhole

A teenage boy has had a lucky escape after falling from rocks at a notorious Sydney blowhole.

The 14-year-old fell off the Warriewood blowhole on Sydney's northern beaches about 2pm on Wednesday, Surf Life Saving NSW said.

His friend alerted lifeguards, who found the boy stranded with minor cuts and bruising on a ledge inside the blowhole tunnel.

The boy and a lifeguard swam out of the blowhole tunnel and were picked up by a jet ski.

"Jumping off the Warriewood blowhole is an extremely high-risk activity and as lifeguards it is something we actively discourage," Australian Lifeguard Service Pittwater supervisor Brad Woodward said.

"The teenager was very lucky as we have been training for this type of rescue scenario and we were able to react quickly and professionally because everyone knew their jobs."

This is the twelfth major incident at the blowhole in the past six years, including the death of a 23-year-old man in 2013.