My long descent into the dark labyrinth is marked by a deathly silence save for the intermittent sound of dripping. A single drop of acidic water is falling fifteen metres every few seconds, resonating eerily within the cylindrical shaft as it strikes a large block of limestone shaped by nature's hand.
I am descending into Ruakuri Cave, two kilometres southwest of Waitomo's main glowworm cave, embarking on a spiritual journey deep into the underworld.
That continuous drop of water falling down through the centre of the spiral staircase that provides access to the cave, can be explained in scientific terms and in ancient Maori symbolism.
Water is the sky element coming from Rangi the Sky Father, falling as rain, passing through the forest of Tane and penetrating porous limestone rock into the underground realm of Papatuanuku, the Earth Mother.
Laying a hand on the cool smooth surface of the limestone boulder I make a symbolic connection with the ethereal world below. A guide then leads our small group into the Drum Entrance airlock tunnel and a whole new dimension.
This world was opened up by dedicated workers with a passion for caving. The sort of passion that drives people to labour for hours in a veritable mud bath, perspiring in wetsuits and laying a bank of forty-four gallon drums in the entrance to ensure they had a safe exit route during the pathway construction phase.
Drum Passage provides a visual feast of curious crystalline shapes. Cave coral, slender straws, flowstone, rimstone and columns are revealed by the guide's spotlight.
We squeeze past two impressive stalactites, which carry $10,000 price tags - that's the penalty that would have been imposed on the operators if the stalactites had been damaged during development. None were.
The high viewing platform over the main stream gives us a view of black water rafters deep down in the narrow canyon, gliding through the inky blackness on rubber inner tubes. Steel gantries suspended on wire cables lead us to Rimrock Junction and on to the shimmering lights of the glowworm colony.
The ghostly bioluminescence of a humble gnat larva called Arachnocampa Luminosa (the glowworm) is created by concentrating phosphorescence on a tiny portion of its body.
The lingering light lures insects into its larder through a curtain of sticky threads. After feeding ravenously the adult gnats emerge to mate, lay eggs and die within three days - an ignominious end for a tiny superstar.
A young bird hunter discovered the original cave entrance by chance over 400 years ago. He was attacked by a pack of wild dogs living in the cave - hence the name Ruakuri (Rua - den, Kuri - dogs.)
Later Maori inhabitants used the cave entry portal as a burial site, so it is now a sacred place (waahi tapu). The burial site is some distance from the new entrance.
The cave is part of a unique karst limestone landscape that was formed under the sea from the solid remains of countless millions of marine creatures around 30 million years ago.
Rainwater and carbon dioxide have combined to form a weak carbonic acid, which has seeped through fractures and slowly sculpted streams, sinkholes, springs, arches and fluted rock outcrops. Beneath Waitomo's lush green pastures lie hundreds of kilometres of labyrinthine tunnels and chambers that have only partially been explored.
As our group continues through the cave I become aware of a distant rumbling sound. This alien realm holds secrets and in these partial blackout conditions one's imagination can take hold. Am I hearing the muffled voices of long-departed ancestors buried in the cave, the low growl of a pack of wild dogs, or perhaps the distant thunder of a hidden waterfall?
John Ash, a geology consultant for Tourism Holdings Limited tells us "quite a few people have had interesting experiences in the cave - it certainly has a 'presence' and mana (authority) that is palpable".
One incident was reported when electricians were repairing lights in the cave. They heard footsteps and decided to be 'Smart Alecs' and hide in a cleft. The steps went right past them and faded but they saw no one. The sparkies turned very pale and made straight for the exit.
The Cave Manager tells me Ruakuri Cave is a mysterious place and sensitive people do pick up inexplicable vibrations and sense the "presence" of the cave.
"Streams and waterfalls reverberate through the caverns and people imagine they hear voices at times."
The second half of the underground journey includes a short side path to view The Pretties, a miniature gallery of flowstone, stalactite straws and other delicate sparkling formations. The dark corners of the cathedral-like Holden's Cavern are a suitable place to linger and test the sounds of the vast echo chambers.
People of all ages and all physical fitness levels can have the experience of entering this underworld universe.
Our guide advises us to "let the cave speak for itself". To me it speaks eloquently of mystery, timelessness and the secrets of an unknown but palpable spiritual presence.
It is truly a fairytale world of spirals and speleothems, stalactites, old fossils and young glowworm superstars.
These lively luminaries continue to draw flying insects and human travellers into their lair. Long may they reign in the wondrous world that lies beneath.
IF YOU GO
Tour information: Ruakuri Cave tours depart daily at hourly intervals from 9am to 3.30pm.
Duration: Approximately two hours (1hr, 30mins underground).
Departure point: Tours depart from The Legendary Black Water Rafting Co. at 585 Waitomo Caves Road, Waitomo Caves, SH37.
What to bring: Comfortable walking shoes and a warm jacket.
Special note: Photography and video are permitted in selected areas of the cave.
Further information: See waitomotourism.co.nz.