A family swimming at Ruakaka beach left the water at top speed after they turned to see what had caused a loud splash and saw a shark "frolicking" nearby.
Emma Whyte said the splash made by the over 2-metre long shark they believed was a mako was loud enough to be heard above fairly rough surf yesterday at about 3.15pm.
Ms Whyte, who was in the water with two of her children and her sister-in-law, said the shark was about 100 metres from them, and was between the beach and the crab pots it may have been trying to dine on.
"We ran. It was freaky," she said.
"It really looked as if it was frolicking in the waves. The splash it made was huge and that was over the top of the sound of the waves."