International Travel

Thu, 21 Dec, 2017Danielle McCarthy

The life-changing experience of diving the world’s largest sea cave

The life-changing experience of diving the world’s largest sea cave

Sue Halliwell is a New Zealand-based travel writer from Whangarei, specialising in eco-adventures and travel for the 60-plus age group. In this piece, she returns to the spectacular Poor Knights Islands off New Zealand’s Tutukaka Coast to fulfil a dream and conquer a deep, dark fear. Find more of her work here.

I had just emerged from the waters of the world’s largest sea cave.

Helping haul my wetsuited body back on board Pacific Hideaway, boat master Glenn held his hand up for a congratulatory high five. I obliged, although he couldn’t have known how big this actually was for me. Not only had I just fulfilled a long-held dream, but I had also conquered a deep, dark fear - or more correctly, a fear of the deep and dark.

This was my second trip to the Poor Knights Islands Marine Reserve. Five years earlier, I had left this extraordinary place feeling disappointed - in myself, not the islands. This striking 12-island archipelago punctuating Northland’s eastern horizon can’t fail to impress, but I was less than happy with my failure to do what I had yearned to do there. So, when offered a second chance at it by Yukon Dive, I grabbed it.

Since reading about the Islands’ famous Rikoriko Cave decades ago, I had longed to sing there. I’m no Kiri Te Kanawa, but I dreamed of filling all 200,000 cubic metres of the biggest marine cavern in the world with song, and hearing it chorus back to me off the walls. What’s more, I wanted to sing Amazing Grace in this cathedral-like natural sound shell, because it seemed the most appropriate choice of song.

However, to do this would potentially mean swimming in the cave’s inky, fathomless water, a prospect that terrified the flippers off me. Now sitting on a boat bound for the Poor Knights about to get that opportunity, I wondered if this time the joy of soul singing would conquer my phobia of being in shadowy water. I hoped so.

Image 1 Sea Cave

Aerial shot of the Poor Knights Islands. Photo credit Ian Skipworth and Yukon Dive.

I spent the journey distracting myself by looking for the many whale and dolphin species that swim this coast. Yukon Dive’s stable catamaran, Pacific Hideaway, provides the perfect platform for whale spotting, and is a popular choice for visitors wanting to explore the Poor Knights Islands in comfort. Making the 23-kilometre voyage there from Tutukaka every weather-appropriate day in the summer season, Yukon Dive owners, Jo Thomson and husband Noel Erickson, know the route and the islands well.

“To us the Poor Knights offer an unparalleled experience, both above and below the water,” Jo says.

“It is a place of huge ecological, historical, cultural and geological significance, with something new or different to see on every trip, and we love that we get to share that with others.”

Those others are increasing in number.

“Our passenger numbers are up on previous years,” Jo says. “Our customers include Kiwis wanting to see and be in a place they have heard so much about, as well as travelers from every corner of the globe with a Poor Knights adventure on their list of New Zealand must-dos.”

Image 2 Seacave

Taking giant strides into the water from the steady platform of Yukon Dive’s catamaran, Pacific Hideaway. Photo credit: Yukon Dive

They come to experience one of the world’s iconic diving spots, rated by Jacques Cousteau as among the ten finest in the world. The eroded remnants of a gigantic 4 million-year-old rhyolitic volcano standing 1000 metres high and stretching 25 kilometres across, these craggy, steep-walled, cave-riddled islets and their waters out to 800 metres provide legal sanctuary for its terrestrial and marine inhabitants.

The fish, at least, appear to know it. Since the Poor Knights Islands Marine Reserve was created in 1978, their numbers have exploded. Department of Conservation fish monitoring over the first ten years of Reserve status revealed snapper numbers had increased 14-fold, with large numbers of other fish species also arriving in the islands’ temperate waters and staying, including sentinel species like hapuku, or grouper.

This pelagic profusion was very evident on our first dip into the water at ‘The Gardens’, to the left of Rikoriko Cave. Donning the supplied wetsuits and snorkel or dive gear, we slipped into a surprisingly clear ocean, to be greeted by huge schools of milling blue maomao and pretty pink demoiselles.

As I got closer to the undersea cliff walls, varietal seaweeds came into view, bending and bowing with the swell, and harbouring fish of all size and description. One large and curious snapper even hung out within touching distance of me for at least ten minutes, an intimate fish connection that I have never before experienced.

Image 3 Sea Cave

Milling schools of fish like these demoiselles greeted us as we entered the water. Photo credit Ian Skipworth and Yukon Dive

Back on the boat and after circumnavigating the second largest island, Aorangi Island, my moment of truth and Rikoriko Cave arrived. As the Pacific Hideaway slipped quietly into the huge cliff cavity, Noel came to the front of the boat holding a beautifully carved Maori trumpet, or pukaea. Lifting the traditional instrument and blowing, the cave’s natural acoustics gathered up and hurled the haunting sound to its perimeters and back again. I was captivated.

The boat’s thirty or so passengers fell completely silent, and had I wanted to break the spell I could have launched into Amazing Grace there and then. But the moment was too sublime to fracture with singing of my quality, and I remained silent. Looking into the cave’s black waters I knew that swimming back into them would be the only way to achieve what I had come to do, and tried hard to swallow my fear.

Image 4 Sea Cave

Assorted anemones, starfish and gorgonians , pink maomao and a splendid perch enjoy the Poor Knights Islands Marine Reserve. Photo credit: Ian Skipworth and Yukon Dive

Outside the cave and the boat at anchor, I watched as other passengers prepared to explore Rikoriko’s delights for themselves. Sensing my trepidation, two onboard friends invited me to join them. Buoyed by this support, I took a deep breath and dived into both the ocean and my phobia.

On the short trip from boat to cave, laser-like shafts of sunlight pierced the water in every direction, highlighting the translucent scales and colours of the fish around and below us. It was an exquisite sight, however the rays died suddenly just inside the cave entrance, and with it my courage. Fighting panic, I sidled up to one of my pals for comfort, swam alongside her into the cave and watched in awe as a magical world opened up to me.

Despite the dark, I could clearly see the multi-hued and multitude of sea urchins and anemones on the cliff wall, the schooling blue maomao and another snapper shadowing me as if in protective escort. Further and further into the cave I went, until I found myself at its centre feeling surprisingly calm.

Throwing caution aside, I opened my mouth and sang the first verse of Amazing Grace with all the gusto available to someone who must also tread water. While I can’t claim to have created the spectacular effect of Noel’s pukaea, I could still hear my voice echoing round the cavern and hooted in celebration.

Image 5 Sea Cave

The world’s biggest sea cave, Rikoriko Cave on the Poor Knights Islands, from the inside out. Photo credit: Bryan Halliwell

I then surprised myself further. My friends had swum deeper into the cave to look for the sunken jaw bone of a whale that Noel told us rested on the sea floor, and I followed. The bone located, I swam slowly back toward the light, revelling in the growing richness of colour and life around me and also that I’d had the courage to be part of it.

So, when Glenn congratulated me, he didn’t know the half of it, and I suspect that’s the case with many of his passengers. In exploring one of New Zealand’s most intriguing and significant island chains, they venture into unexplored places in themselves – perhaps as big as Rikoriko Cave itself – to find that the dark and deep, once conquered, become delight.

Waters around the Poor Knights Islands to 800 metres are a marine reserve, which means:

  • No fishing of any kind
  • Don't take or kill marine life
  • Don't remove or disturb any marine life or materials
  • Don't feed fish - it disturbs their natural behaviour

For more information on Yukon Dive’s scenic, snorkel and dive trips to the Poor Knights Islands Marine Reserve, go to