A "massive" rip off Dunedin's St Clair beach swept six surfers hundreds of metres out to sea on Monday.
Two exhausted teens needed rescuing after battling the rip for 45 minutes.
The incident has prompted lifeguards to warn people who are inexperienced or unfamiliar with the Otago coast to seek advice from lifeguards or local surfers before taking to the water.
Rips off St Clair and St Kilda beaches were common, but this "extraordinary" example was caused by easterly winds, St Clair Surf Lifesaving Club chairman Anthony Mason said yesterday.
Stretching about 600m out to sea from the south corner of the beach beside and seaward of the St Clair salt water pool, the rip was choppy, fast and dangerous.
"At low tide, it looks like a fast-flowing river."
Surf lifeguards had been keeping a careful eye on the rip and people near it following the discovery about 4.30pm on Monday of a group of surfers about 300m offshore who could not escape it.
While another lifeguard who came to assist returned to get an inflatable rescue boat, Mr Mason and friend Phil Pirie, who were training on surf-skis, were able to tow two people to safer water.
Two Dunedin schoolboys, aged 15 and 17, who had been struggling against the rip for about 45 minutes, were taken back to shore in the rescue boat.
"They were [extremely tired]."
The others stuck in the rip managed to follow Mr Mason and Mr Pirie out of the fast-flowing water under their own steam.
The surfers were not all known to each other and, aside from the schoolboys, were new university students and European visitors to Dunedin.
"I think the message here is the Otago coast varies so much and, while that can be the attraction, anyone new to Dunedin should always, at the very least, talk to lifeguards or local surfers before getting in the water," Mr Mason said.
