Surf Life Saving NZ has encouraged people heading to the coast this summer to beware of beaches that may have changed since their last visit.
The organisation said swimming conditions could be dangerous because of major changes caused by large weather events.
Raglan's Ngarunui Beach, famed for its big waves, was one of the beaches affected by this change.
Northern Region lifesaving support officer Corey Harvey said there had been multiple mass rescues this season.
"Because of the changes in the beach, Raglan here is seen to be more dangerous than it has in the number of years," he told 1News.
"We have seen a number of mass rescues already here at Raglan where we've had groups of people going into the rips and then lifeguards that unfortunately had to rescue them."
Rips were a common danger for beachgoers in New Zealand.
They form when water from breaking waves seek the path of least resistance to drain out to sea, producing a dangerous vacuum that can pull swimmers out.
The depth and the shape of the seafloor affect rips, with deep seabed holes formed by severe weather creating a surplus of rips and consequently, a surplus of rescues.
Raglan Surf Life Saving has also faced the negative impacts of severe weather onshore, with erosion eating away at sand dunes at higher rates than in previous years.
This sand is then carried north and deposited onto Auckland's west coast beaches such as Piha and Muriwai.
Raglan's beach patrol tower has been closed as a result, with monitoring taking place from on the beach or from the club.
"What we do is we have our lifeguards up here on the tower, having the birds eye view, and we have lifeguards still on the beach, watching the flags and being in our swimmers are there," Harvey said.
Beaches in the Waikato, Canterbury, and Bay of Plenty regions were all experiencing similar erosion.
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