At the back of the old cow shed which serves as the information centre for Wairere Boulders and gateway to its extraordinary rock formations, there is a camp bed especially for geologists.
What's that for, I wonder. "Well," says Rita Schaad, "it is because when geologists come here they often need a lie down."
I can't stop myself from asking why ... and Rita is delighted to explain. "Usually when geologists come here they look at the rock formations and say, 'That is very interesting fluted rock. Is it limestone?' And I tell them, 'No, it isn't limestone.'
"Then they ask, 'What is it?' That is when I tell them, 'You might need to lie down.' If they don't want to lie down then I say, 'Well, you asked for it,' and I tell them, 'It is basalt.'
"That is when they freak out because they know you can't have fluted basalt. We have had professors here who have always taught their students that it is impossible to have fluted basalt. But here it is right in front of their eyes."
Wairere Boulders, on the Schaad's farm near the historic Hokianga town of Horeke, has been open for six years and attracts 6000-7000 visitors a year.
Most just come to admire the remarkable shapes of the great river of volcanic boulders, covered in moss and lichen and flowing between lovely stands of bush, which was thrown across the property by the eruption of Lake Omapere some 2.8 million years ago.
But some of the visitors are, indeed, geologists who come to stare with disbelief at the fluting - deep cuts up to 1m deep and 300mm wide leached into the hard volcanic rock - which apparently doesn't occur in basalt anywhere else in the world.
Not that Rita and husband Felix knew any of this when they bought the property 26 years ago. They were just looking for a wilderness, somewhere totally different to the manicured beauty of their native Switzerland, where they could build the sort of life they wanted.
"Of course we could see there were some rocks down at the bottom here," says Rita, "but the rest was just covered in trees.
"The locals said to us, 'You are mad to buy that land, it has rocks sticking up everywhere, you can't do anything with it.' But we thought it was a beautiful wilderness and it was what we wanted so we came here to live."
Also on the land when the Schaads arrived was a large herd of wild goats which - as goats do - ate everything in sight. "As they ate the plants," recalls Rita, "more rocks appeared and the more we saw the more beautiful we thought they were."
Visitors to the farm also admired the rocks, so about 10 years ago the Schaads decided to turn them into a proper tourist attractions. For four years they developed a network of tracks, built bridges - 24 of them - and created an information centre.
Today tourists are able to wander around, under, over and even inside the boulders, admiring the shapes and stroking the curved sculpted shapes, savouring the tranquillity of the bush with its prolific birdlife and peaceful pools of water, scrabbling through dark caves and up stone staircases, enjoying Wairere Boulders for its simple beauty.
However, at the same time as they were building the paths the Schaads researched the nature of their rocks and how the volcanic basalt came to be sculpted into so many amazing shapes.
At first their approaches were dismissed by geologists because basalt rock was considered to be impervious to leaching.
But finally it was accepted that, yes, these rocks were basalt and, yes, they had been weathered into what a recent newsletter of the Geological Society describes as "flutings or lapiez and solution pits of outstanding size and beauty".
The same newsletter concludes that the rocks must have been shaped by extremely acidic runoff caused by the vast kauri forests which once covered this area, though it also urges that further research be carried out because "there are many more questions about the formation of the valley and the cause of the surface erosion unanswered".
Despite that recognition sceptical geologists keep arriving and rejecting the evidence of their own eyes ... and some require a lie down.
But such scientific matters don't bother the Schaads or their visitors. "We didn't know it was unique," says Rita. "We just knew it was beautiful. That is why we created this park."
Jim Eagles visited Wairere Boulders as guest of Destination Northland.