Shark sightings over the last two weeks may be due to the El Niño climate shift and has prompted reminders for swimmers to take caution.
Lifeguards recorded more than 40 first hand sightings of sharks across two regions in the past fortnight, Surf Life Saving said on Tuesday.
And while lifeguards were used to sharing the water with sharks and most of those seen were not big enough to cause alarm, Surf Lifesaving eastern manager Chaz Gibbons-Campbell said, he warned people to be cautious.
"In the last two weeks we've had 42 sightings across Coromandel and Bay of Plenty. That's from lifeguards seeing sharks swimming by, and most of them are on the small size range, so sort of under a metre and a half."
Marine scientist Riley Elliott told RNZ the El Niño climate shift meant warm, fish-rich waters were just now coming into shore, and with it, more sharks.
"This summer is quite different to last summer in that it's cooler water, the ocean's a little bit slower behind in its productivity because of the shift to El Niño.
"We are starting to see that warm productive water come in, more and more fish coming in closer to shore, and with that, shark sightings."
Dr Elliot said it was worth nothing that while warmer, productive water was more inviting to sharks, there were also more people around beaches through summer to see them.
Hastings man Timothy James Carrington got some close snapshots of a shark he estimated was about 2 metres long, and only about 2 metres from the beach at Whirinaki, north of Napier, on Tuesday.
He posted the photos to an online community group to warn people to be careful.
"It was in very close. I walked down the beach to tell a dog owner that was throwing sticks into sea [for his dog] ...that he was throwing the stick further out than shark was."
It was hard to tell what type of shark it was, he was, and many people had guessed it was a bronze whaler, but Carrington himself thought it could be a blue shark.
Gibbons-Campbell said surf lifesavers even though the vast majority of sharks likely to be encountered at the beach were harmless, people should take safety precautions to keep safe.
"Don't swim where people are fishing ... and avoid swimming at dawn and dusk," when sharks are feeding, he said.
And, "around fishing... make sure that you are disposing of your fish carcasses appropriately, by not dumping them in the ocean."
This was echoed by Dr Elliot, who added that people should use "common sense" if they saw a shark, and follow directions of lifeguards to move safely out of its path.
And Department of Conservation marine scientist Clinton Duffy told RNZ the best way to stay safe if you spot a shark is to get out of the water as quickly and as quietly as possible.
A teenager was killed in a shark attack late in December off South Australia's coast. And several shark attacks had also already been reported in New Zealand waters this summer, including on the Wairarapa coast and in knee-deep water in a Southland estuary.