Dune hoons are allegedly driving other beach-goers off the Pouto Peninsula on the Kaipara Harbour.
Auckland-based author Matt Elliott has close family-ties to the area and visits regularly.
He told Checkpoint four-wheel drivers and off-road bikes were dominating Ripiro Beach, driving irresponsibly, and leaving behind their waste.
The stretch of beach is legally a road which complicates any crack down.
Elliott said it was particularly bad on Friday at Glinks Gully, near the Redhill township.
"These four-wheel drives were congregating at Pouto, it was obviously a very well-organised meet of these guys and their vehicles and there were just literally swarms of the vehicles going down the beach and down the Pouto Road to meet down at Pouto."
Safety of beach-goers was one of the main concerns, he said.
"There was actually a near-miss with a motorbike.
"A family had come out to spend the day out at Glinks Gully and a motorbike went through the dunes only seconds after a two-year-old had gone walking in that area and totally frightened the living daylights out of the parents who packed up and left the beach.
"There was a fatality at the beach - a similar sort of scenario - 15 years ago.
"So there's a lot of concern and worry about something happening again because these guys on their bikes in the dunes and cars on the beach, they've got no consideration for anybody else.
"The real, real concern is about the possible dangers to people, innocent people who are out at the beach, and the drivers themselves because they're not observing how they should drive on the beach in terms of where they are on the beach and so on."
Daisy Fernandez, 13, died after being struck by a motorbike on Glinks Gully on 31 December, 2007.
Another issue for those living nearby and frequent beach-goers has been the waste left behind, Elliott said.
Among the items picked up by residents and bach owners were discarded bottles and wet wipes used for going to the toilet, he said.
"There have been bonfires that have been built and they've been so hot that all the glass bottles that have been thrown in there have just melted, so there's enormous amounts of waste that has been left behind and then picked up by other people."
The Department of Conservation has previously warned motorists about taking care around wildlife on the beach after a seal died as a result of being hit by a vehicle in 2018.
The public is advised to stay at least 20m from any seals they encounter, and to keep dogs and children away from them.
Elliott said a relation of his spent an hour trying to protect a seal from four-wheel drives going up and down the beach on Saturday.
"When they get off-road and they're going up the cliffs in the dunes, the erosion is extraordinary.
"It's driving the farmers wild because when the winds come up, the sand is blowing up onto the paddocks - huge environmental issue."
Police said they had heard anecdotal reports of some issues around behaviour of drivers in the area.
