I AM GLIDING silently across a lake, gazing up in wonder at a night sky dotted with thousands of twinkling stars. It is a breathtaking sight.

Except that I’m deep underground, and the stars are not what they seem. They’re carnivorous critters sneakily seeking their prey.

It sounds like a scene from a science fiction B-movie – but it’s not. Because this is an A-list travel bucketlist attraction, Mother Nature at her finest.

I’m in the Glowworm Caves at Waitomo, in New Zealand, on a magical mystery tour that outshines anything Jules Verne or James Cameron ever dreamed up. A real-life Avatar.

Thirty million years in the making, and a tourist attraction for more than 130 years – the blink of an eye in the grand scheme of things – this is one of those few places on Earth you have to see to believe.

And, defying the odds, the caves are still open in the Covid era, visitors protected by an array of health and safety precautions.

The star of the show here is Arachnocampa Luminosa. It sounds like a Harry Potter Hogwarts spell but is actually the scientific name for remarkable glowworms unique to New Zealand.

Growing as long as a matchstick and looking like a tiny worm, a bioluminescent glow emits from its tail, sparked by a reaction between the creature’s chemicals and oxygen in the air.

The clever critter can control its brightness by reducing oxygen to its light, attracting insects which get caught in sticky ‘fishing lines’. And, bad news for prey, there are countless thousands of them down here.

Immediately upon hatching, the larvae switch on their lights, build a nest, drop down lines and feed. They need to make the most of it because, after nine months, they turn into a fly a bit like a large mosquito.

But the adult fly has no mouth or stomach and only lives a few days – if it isn’t devoured by the other glowworms first. It is one of the strangest stories Mother Nature has to tell.

There’s plenty of explanation at the striking visitor centre – it’s designed to reflect the curve in the Waitomo River and the contours of the land – before you set off on your underground expedition.

Wear something warm, although it’s 16-17ºC year round in the caves, and take a comfort break before you set off in a small group with your guide. 

Initially you may feel a tad underwhelmed and wonder what all the fuss it about. The upper levels of the caves are not as impressive as some you’ll have visited – but appearances can be deceptive.

After making your way down through the evocatively named Catacombs, Banquet Chamber – where early visitors stopped to eat – and Pipe Organ, with their myriad stalactites and stalagmites (‘c’ for ceiling; ‘g’ for ground, remember) magic awaits.

The levels are linked by the Tomo, a 16m vertical limestone shaft – but don’t be daunted.

I descend along atmospherically lit paths smoothed by generations of explorers and visitors, with occasional glass-sided staircases allowing easy access to The Cathedral, a soaring spectacular subterranean sight.

Dame Kiri Te Kanawa, Katy Perry, Rod Stewart and UB40’s Ali Campbell are just a few of those who have sung down here, and there’s an annual Christmas carol concert during which Santa abseils from the caves above.

The limestone of the 18 metre-tall cave absorbs all vibration, creating perfect acoustic conditions. Our guide invites us all to sing and shout and, even in such a cavernous space, there are no echoes.

But all this has been just the build-up to the main attraction. We’ve had tantalising glimpses of the Waitomo glowworms as we’ve crouched to peer through a low window in the cave walls.

Now, a final flight of stairs leads down to the shore of an underground lake straight out of Verne’s Journey To The Centre Of The Earth. A small boat, capable of holding around a dozen people, awaits.

We’re asked to remain silent and not take any photographs because the glowworms do not like to be unduly disturbed. It’s respect for these Waitomo wonders but also makes the whole experience more magical.

Our guide stands at the prow of the boat, punting us out onto the lake. As the light from the landing fades the ceiling of the cave begins to twinkle like a night sky unsullied by light pollution.

It’s as if the Milky Way stretches out overhead. The only sounds are gasps of awe from my fellow passengers and the gentle murmur of our boat gliding across the water. It is inky black both above and below.

When we stop in the middle of the lake, our guide extinguishes his lantern and the tiny lights are reflected in the water. It’s as if we are suspended in space, an experience like no other. One of those truly unforgettable moments in your travels.

It must have seemed near-supernatural to Maori chief Tane Tinorau and English surveyor Fred Mace when they first explored these caves in 1887.

Local Maori people knew of the caves’ existence, but they had never been explored until the pair built a raft of flax stems and, with candles as their only lighting, floated into the cave where the stream goes underground.

Their first discovery was the Glowworm Grotto. As their eyes adjusted to the darkness, they saw a multitude of lights reflecting off the water. Looking up, they discovered that the ceilings were covered by the glowworms.

By 1889, Tane Tinorau had opened the cave to tourists, he and wife Huti escorting visitors for a small fee. In 1906, the administration of the cave was taken over by the government.

But in 1989, almost 100 years later, the land and the cave were returned to the descendants of the original owners. Many staff employed at the caves today are direct descendants of Chief Tane and Huti.

All too soon, we glide around a rock formation and moor at another landing, then a short walk leads to a crack in the caves and we emerge into daylight, making our way back up to the visitor centre.

If you’re feeling even more adventurous, sister caves Ruakuri, with its deep spiral pathway, and Aranui each offer different sights, and black water raft trips take safety suited and booted visitors through the system.

The Waitomo Caves are in the North Island’s rural Waikato area, around an hour from Hamilton, and two and a half hours from Auckland. I stayed in Cambridge, a small town handy for both the caves and Hobbiton, the film set used by Peter Jackson for his Lord Of The Rings and Hobbit trilogies.

For the latest admission, availability and Covid updates for Waitomo Caves see www.waitomo.com. For tourist tips, stop off at www.newzealand.com, the home of Tourism New Zealand.