Cunningham said the water at Waipū Cove was riddled with small fish when he waded in ankle deep water on his way out to surf.
"I heard people screaming behind me but couldn't quite make out what they were saying. Then I saw people running towards the beach and saw this thing ... a 2m-plus bronze whaler," he recalled.
"It was quite still at that point and then it started thrashing around, just trying to catch fish. It wasn't interested in people."
Cunningham said he got out of the water and watched with about 100 people as the bronze whaler went up and down the waves catching fish for about 20 minutes before it disappeared further out into the ocean.
He said some people went back in the water about 30 minutes later but most stayed out.
"It was quite a neat thing to see. I wasn't freaking out but was definitely cautious. I think it's more a case of they being there all the time but because more people are on the beach at this time of the year, there are more sightings."
It was the second time Cunningham had spotted a bronze whaler.
The first was about 10 years ago while surfing at Sandy Bay and the bronze whaler went around the surfboard in circles before disappearing.
Shark expert Clinton Duffy said bronze whalers were common and could be seen dotted in shallow waters along the upper North Island's east coast.
"They have relatively small narrow teeth mostly for eating fish and are generally no trouble for swimmers but they can behave aggressively towards spear fishers and occasionally bite them."
He said people should get out of the water quickly and quietly if they saw bronze whalers.
In October, Whangārei surfer Andrew Brough was attacked by a great white shark at Baylys Beach, near Dargaville. The 25-year-old has undergone surgery for deep bite wounds to his left arm.
Just before Christmas, Kevin Lloyd was attacked by a 2.1m mako shark while spearfishing with friends near the Cavalii Islands. He stabbed the shark in the head while his friend held on to its tail.
