A man has fallen off algae-covered rocks in the same spot at Muriwai Beach where another was seriously injured and a fisherman died.
The Otahuhu resident lost his footing on the rocks around 11am and plunged into the water, but managed to escape serious injuries.
Muriwai lifeguards said the man removed his clothing to remain buoyant. His fisherman mate reached out his rod so that he had something to hold onto until lifeguards arrived.
The man was treated for minor cuts and abrasions.
"The real safety issue on the area known as Flat Rock is the clear and present danger of various algal growths at numerous points on the rock," said Tim Jago, Muriwai Lifeguard Service chairman.
"The green algae is growing thickly in several places and is deceptively slippery. Worse are the black and brown film-like growths that are almost indistinguishable from the rock itself."
The algae, which becomes wet from rain, waves or sea spray, creates and ice-like layer that is almost invisible.
Rock fishers have been advised to wear life jackets and personal flotation devices.
On Tuesday, a man died at the same spot after falling off the rock.
Kovati Vaoga, 21, was not wearing a lifejacket and lifeguards said his death was preventable.
Surf lifesavers recovered his body about two hours later in the gut, an area close to where he fell in.
Earlier last month a man aged in his 30s slipped on a wet rock and tumbled 4m into a blowhole.
Another person had to be rescued after falling down a blowhole at the beach in September.
This morning's fall happened 90 minutes after Auckland Council staff and lifeguards installed a mounting device to which an additional life saving flotation device - known as an Angel Ring - will be fitted later today.
However, signs warning fishers of the danger which were erected on Thursday have already been vandalised.
- Auckland Now