Waitomo Trail Run race director Tim Day was worried about apathy in the running and walking communities.
"Trail runners visit so many cool places that they can become a bit blase about what they are experiencing over time. If you see great views every weekend, it's easy to become desensitised," says Day.
"We wanted to create a unique, mind-blowing experience for people - something mysterious, but accessible and manageable for all ages and abilities, from beginners to children."
It wasn't long before Day's attention shifted to the surreal subterranean world where he was raised, close to Waitomo.
"Growing up in the King Country, I learned how to adventure. Crawling around in caves and underground rivers with candles, you find out about yourself. Many people have visited Waitomo Caves and had the tourist experience - but it's not raw, it doesn't force you to confront yourself. Where we are going, you feel isolated, even though you are actually not far from the road."
Co-organisers Paul Charteris and Day called on Angus Stubbs. Stubbs Farm has been in the family for 101 years. Lying at the headwaters of the Waitomo catchment, it has one of the highest concentration of sinkholes of anywhere in the world, according to GNS scientists.
Acutely conscious of a need to protect the delicate limestone topography and wildlife endemic to the area, Angus' father Alistair covenanted 250ha as a QEII National Trust block back in the 1980s. Since then, thousands of school children, spelunker and bouldering groups, research students and scientists have visited Stubbs Farm. Some come for adventure. Most come to study the cave systems and flora and fauna.
"Over the years, we've had every kind of scientist from entomologists to ornithologists. At the moment, harvestman spiders and peripatus [walking worms] are drawing a lot of interest. We fenced the QEII block off to keep the stock out and since then, the quality of the forest has improved, including the bird and insect life."
When Charteris and Day knocked on Stubbs' door and proposed a running and walking event through the property, he jumped at the chance to share the family gem with a different subset of people.
"Our family have always known this is a beautiful place. My brother Ben runs our sheep and cattle operation but my parents, uncle, sister, brother and myself still live on the farm - we fell in love with it and can't leave. The beauty of this particular landscape is just phenomenal."
Charteris says he and Day were blown away.
"Angus showed us around and we could hardly believe our eyes: tomos, karst hilltops, caves, tunnels, canyons, sinkholes - it was even more amazing than the maps suggested."
On April 30, runners and walkers participating in the inaugural Waitomo Trail Run will celebrate an aspect of New Zealand's geology that attracts more than 400,000 visitors each year. Passing through a mixture of public and private land, participants will discover the "hidden Waitomo" and its glow-worms, caves, canyons, stalactites and native bush.
Four distance options, ranging from 6km to 33km, weave under, over and through the country from Mangapohue Natural Bridge to the Waitomo Glowworm Visitors Centre. The short courses start underground in Ruakuri Cave and the longer distances include adventure options such as caving.
"No one will be racing this event - most will be on an adventure," laughs Day.
Stubbs looks forward to hosting it.
"We covenanted the QEII block to preserve it for future generations to enjoy - allowing people to experience it in this way is fantastic. Our family will be out there on the day, probably manning a water station."
Waitomo Trail Run
What: 6km, 16km, 22km or 33km run or walk
When: Saturday, April 30
Where: Waitomo, King Country
For more information: www.waitomotrailrun.co.nz