Searching for glow worms in New Zealand's Waitomo Caves

It takes just minutes for the earth to swallow me whole as I abseil into the cave’s mouth. My feet bounce off rock until suddenly the wall slopes away into a yawning cavern and I’m kicking out at open air. With no natural light to see by, I slowly lower myself down through the black abyss until my toes find the comfort of solid ground. 

My careful descent is soon replaced by an exhilarating rush of cold air as I zip-line across a chasm in total darkness. In the distance, I can see head torches growing brighter as I soar across to my fellow cave explorers, enjoying tea on a narrow ledge. Kitted out in wetsuits, helmets and harnesses, they look like a crack team of Navy SEALs at a picnic. 

All around us is the pale limestone rock that’s so abundant in the Waikato region of the North Island, a two-hour drive from Auckland. A popular spot for caving enthusiasts, Waikato’s grottoes were first formed underwater 30 million years ago by the bones and shells of marine fossils, which hardened to create sedimentary rock. Propelled by shifting tectonic plates and volcanic eruptions, the limestone rose out of the sea and, over time, rainwater acidified by the atmosphere carved the channels, caverns and ledges. The result is a still largely unexplored network of perhaps around 1,000 caves, of which only around 300 have been mapped.

“The local Māori people knew these caves existed but were wary of them because they were considered to be portals to the underworld,” says our guide, Logan Doull. “It was better to keep away than go beyond the reach of daylight and meddle with the spirits.” 

Māori chief Tane Tinorau was the first to explore the caves, by candlelight, on a flax raft in 1887. Since then, expeditions have unearthed a trove of scientific and cultural discoveries, including cave art and the skeletal remains of the moa, an extinct relative of the emu that was endemic to New Zealand. 

“It wasn’t until people went caving and found these bones that we realised the extent of wildlife extinctions in New Zealand after human arrival. It’s what you find in caves that really gives us a window into the past,” says Logan. 

With tea done, I jump from the ledge onto a chain of rubber tubing donuts waiting on the underground river below before floating off into the darkness. Deprived of light, my other senses come into sharp focus. At first there’s only the smell of damp earth against a soundtrack of rushing water, but soon my eyes adjust, and a new cosmos emerges overhead. Hundreds of tiny lights pop into view, illuminating the cavern with a faint green glow. These tiny star bursts are native glow worms that use the light emitted from their bodies to lure insects. Looking closely, I can make out their sticky, silken fishing lines suspended in the gloom, waiting for passing prey. 

I lose track of time gazing up at the twinkling lights; it comes as a rude awakening when the ride suddenly ends. Like Alice on her adventures in Wonderland, we next negotiate a series of progressively shrinking caverns until we reach a small slit in the rock. “It’s just large enough to crawl through,” notes our guide with a grin. 

On all fours, I edge my way through water so cold it numbs my hands. At last, the cave opens out again to reveal daylight pouring in from a small opening at the top of a waterfall. Hand over hand, I climb against the surging current until someone grabs my wrist and pulls me from the underworld. Sitting in the sunshine and eating spoonfuls of hot tomato soup, I can only wonder if heaven is half as much fun. 

How to do it

Discover Waitomo’s five-hour Black Abyss caving experience is available year-round. Glow worms are most abundant in summer (December to March). From NZ$265 (£138); minimum age 12.

Published in the Jan/Feb 2022 issue of National Geographic Traveller (UK)

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