A group of surfers went out into the water at Mount Manganui on Thursday morning, seen in footage supplied by Matthew Davison.
"I couldn't believe they were surfing after all the warnings from Civil Defence," he told Newshub.
About 3 or 4 people were surfing at beach at about 10:00am, and another person got into the water but "got a bit scared and turned around."
Mr Davison says a cordon was set up at the Bay of Plenty beach shortly after, with a security guard turning people away from the water.
He was at the beach because he's "a bit of a storm chaser" and is now at Whiritoa on the Coromandel Peninsula.
He says at Whiritoa the winds are picking up, with a lot of surface flooding and things are getting progressively worse.
There are heavy rain warnings for the Coromandel Peninsula and the Bay of Plenty, as well as warnings of heavy rain and strong winds with gusts up 150 km/h.
Coastal areas on the east can expect large waves of 5 metres or more, with storm surges near the centre of Cyclone Cook.
There are also risks of coastal erosion and flooding, and the heaviest rain fall is expected from 3:00pm, with possible thunderstorms.