Two large sharks close to shore cleared swimmers from the water at a Whangarei beach - one of several sightings that have caused lifeguards to close beaches along Northland's east coast.
Sharks have also been spotted close to shore at Waipu, Ruakaka and further south in Omaha.
Auckland couple Andrew and Greta
Glen were among about 20 people who got to watch to large mako sharks cruising within a metre of shore at Smugglers Cove, Whangarei Heads, on Saturday.
"They were about a metre from a rock ledge and swimming up and down. Everyone was pretty freaked out," Mr Glen said.
"There was a couple of people swimming but they got out of the water pretty quickly. The sharks cruised back and forth for about half an hour."
Mrs Glen said that when they had first arrived at the cove they had noticed small fish jumping out of the water and saw a crowd of people on a rock ledge looking down at the sharks below.
"We couldn't see them feeding. It was like they were just curious, checking everyone who was standing on the ledge out."
The sharks appeared to be dark on top but pale underneath. A friend who studied dolphins and had a good knowledge of sharks had told her that they were probably makos, she said.
Northern Lifesaving development officer Andy Kent said there had been several sightings of sharks along the Northland coast and beaches at Waipu, Ruakaka and Omaha were closed temporarily last week after sightings.
"We didn't know what species of sharks they were but as lifeguards we take these things seriously and if they are seen around the patrol area we get people out of the water."
Mr Kent urged caution.
"If a shark is sighted where you are swimming then get out of the water quickly and stay out until the shark has left. If they are seen in a patrol area we will close it down until it is safe to swim again."
But marine environmentalist Wade Doak said swimmers had nothing to worry about.
Shark sightings increased over summer because of the amount of bait fish in shallow waters and an increase in the number of people going to the beach.
There had been very few shark attacks in New Zealand waters so there was very little reason to be alarmed.
Most divers who saw a shark regarded it as a remarkable thing. They were majestic creatures and presented very little danger.
