Off roaders from throughout New Zealand converged on Auckland's Woodhill forest for a weekend of mud.

A "mosh pit" contest for mud loving drivers had to be cancelled after hitting a health and safety snag.

The Woodhill 4x4 Mosh Pit Competition was cancelled and a fun day rolled out instead after a legislation technicality was discovered a week before the Auckland event.

Competition organiser and Polaris 4WD Park owner Roger Winslade says he had to pull the plug after finding the event would fall under the Health and Safety in Employment (Adventure Activities) Regulations 2011.

1 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 2 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 3 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 4 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 5 of 13 Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 6 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 7 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 8 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 9 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 10 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 11 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 12 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill. 13 of 13 Bevan Read/Fairfax NZ Four-wheel-drivers came in droves to the Polaris 4WD Park in Woodhill.

"It was brought to our attention a week out, so we sought clarification."

Winslade found if they charged people to enter the event, and supplied excavators to help pull people out, they would have to comply with the act. Usually his park is exempt.

"It's like if you are a kayak operator and hire kayaks out to people and say – 'here's your kayak, go enjoy', you don't come under the act. But if you teach them how to use it then you will come under it. It's a nightmare for a lot of people."

While the cancellation was disappointing, more than 80 people came for the day out regardless.

Big engines, noisy exhaust and chucking mud around is what brings Rodney 4WD Club treasurer Anthony Barr to the events.

The software test analyst is not alone in pouring thousands of dollars into his truck.

"So far I've spent around $25,000 and it's not on the road yet. I'm guessing around another $5000 will get it on the dirt."

Barr says the sport attracts a wide variety of people with a "very cool culture".

Four-wheel-drive enthusiast Caleb Thompson says people come down just for the fun.

"There are a lot of people that would never have considered four-wheel-driving. We take them out… they have an absolute blast and some of them go out and buy one."

Thompson says he has seen a shift in people joining the sport with a number of former boy racers buying in.

"It has its pros and cons. It's cool to see a lot of new people in the sport. Sometimes they don't all play ball… which is unfortunately a bit of a shame.

"We do our best to get them into a club and teach them the right way and try to keep them out of trouble," Thompson says.

Justin Grieve was one of them. "I lost my licence for extended loss of traction 'cause I used to enjoy Nissan Silvias and drifting. After I did that I decided to buy a little Suzuki truck."

Grieve says when he first started there were no younger guys doing it, but now it's "going nuts".

"It gives you something to do on the weekend... it gives me a good sense of achievement. You meet heaps of cool people."

Chris Blackwood used to drive a R32 Skyline and owned a Nissan Safari as a tow car.

"Everyone said 'come out on the mud in it'… Now I've got a Cefiro that sits in the garage and I bring my Safari here."

Dirt Dolls NZ's Claire Duncan and Samantha Bailey hold their own in the male-dominated sport and say the competition is healthy.

"Men and woman in the truck world are like Nissan and Toyota… There's such a debate between the two of them, but we're all good at what we do, and we do it for the love of it," Bailey says.

Bailey also came from a car racing background, "instead of lowered I wanted it lifted".

"Days like today, you have such an awesome time. It doesn't matter if you break your truck."

* Polaris 4WD Park is one of the only 4WD venues in Auckland with 1012 hectares of varied terrain. Visitors pay a fee and do their own thing.