Gas mask clasped to my face, I stumble through a thick cloud of sulphurous fumes as helicopters circle overhead. It’s not the Apocalypse and is in fact a bunch of tourists on a cruise holiday.
But a visit to White Island, a 200,000-year-old live marine volcano in New Zealand’s Bay of Plenty, is my introduction to the wild, largely uninhabited and relatively unknown outlying islands that hang down like a necklace in the South Pacific Ocean.
Thanks to the absence of any endemic land predators, several ecologists have described New Zealand as being the best example of how life might function on another planet, and in particular, the Subantarctic islands promise to be like nowhere else on Earth.
Far further south than White Island, the five UNESCO World Heritage Subantarctic clusters – Antipodes, Auckland, Bounty, Campbell and The Snares – serve as some of the world’s most important wildlife sanctuaries. Yet of the 1,200 visitor permits available each year, that quota is rarely filled, an indication of just how tricky it is to get here in the first place.
Silversea is one of the very few cruise lines offering the itinerary on its adventure-seeking vessel Silver Discoverer, combining expedition-style travel with the comforts of butler service and Moet & Chandon on tap.
Beginning in Auckland on North Island, we travel south, stopping at places where birds rapidly begin to outnumber people. It’s true that Pitt Island – part of the Chatham archipelago – looks, somewhat disappointingly, a bit too much like home; rolling hills and grazing livestock were a European introduction.
Ten people on the island (a third of the population) are direct descendants of 19th century settler Frederick Hunt from Lincolnshire, and I’m amazed they’ve maintained the strength of will (not to mention the gene pool) to live so remotely for so long.
A sense of isolation becomes more acute during our long stretches at sea, which I grow to love. Although I could spend days listening to lectures, watching documentaries or burning off decadent gourmet dinners in the ship’s hi-tech gym, instead, I choose to be out on deck.
While crossing the Chatham Rise, we see sperm whales spouting 5m diagonal blows, fluking and leaving a trail of smooth ‘footprints’ in the water. Pelagic birds – ranging from graceful, balletic albatrosses, to Wedgewood blue fairy prions and gnarly-beaked northern giant petrels – hang in our slipstream, then disappear into the horizon where grey sea and sky become one. Their swooping flight patterns are hypnotic.
A 15-minute trip through the Bounty Islands, a rare breeding ground for colonies of Salvin’s albatrosses and erect-crested penguins, proves to be the highlight of my voyage. Here the weather becomes challenging and as wind batters the granite outcrops, birds hang in the ledges, literally clinging to the precipice of existence. Fortunately, the storms soon subside and we’re able to explore our next stop, the Antipodes Islands, on a Zodiac tour. Here, waterfalls cascade down columnar rocks, formed like the pipes on a church organ, and trickle over a stratified ‘mille-feuille’ of volcanic ash.
Parakeets hide in the grassy tussocks, and northern rockhopper penguins weave past slithery tendrils of sea kelp snaking in the water. On land, moulting elephant seals are easily mistaken for enormous boulders, and irritable New Zealand sea lions watch us suspiciously.
After so many days at sea, we finally set foot on land at Campbell Island, although we can’t just merrily skip ashore. In 2003, the most southerly of New Zealand’s Subantarctic islands was declared rat free and officials are determined to keep unwanted visitors of all kinds at bay.
Our boots are scraped and dipped in disinfectant, and clothing intimately probed with a vacuum cleaner. Only then are we allowed on shore, where purpose-built boardwalks run through the grassy nesting grounds of 99 per cent of the world’s southern royal albatross population.
The vast ocean void offers little sense of scale, but up close it’s possible to appreciate the sheer size of these mighty mariners who spend most of their lives at sea, only touching land every two years to breed. Yet now, on terra firma, they appear so vulnerable.
They’re not alone. On my way back to the beach, I’m ambushed by some fiercely territorial sea lions, and a camera tripod feels like lame protection.
Far friendlier residents are the yellow-eyed penguins nesting in the dense silver rata forest and bellbirds whose syrupy song is the sweetest music to my ears.
More symphonies from some of nature’s greatest composers are performed on Ulva Island, much closer to the mainland.
Although not part of the Subantarctics, it’s still swathed in primeval forest and, in the absence of predators, is an ornithological paradise.
Above us, parrot-like kaka birds feed on the red flowers of a rata tree, while below, a Stewart Island robin hops on the ground to mimic rain and lure out worms. We sit a metre away and he doesn’t even flinch.
Once home to neighbouring Stewart Island’s first post office, people would sail here to collect or send mail and spend the day enjoying nature. Volunteer guide Kari Beaven shows us the tough leaves of muttonbird scrub, used as “the first postcards” and legally franked until 1970.
Thousands of miles from home, I wonder how many months it would have taken to send a letter – or even leaf – across the globe.
Even today, New Zealand’s Subantarctic environments are so far from our own reality. True, you have to travel far, but fortunately not to another planet.
• Sarah Marshall was a guest of Silversea (www.silversea.com) which offers a 14-day trip from Auckland to Dunedin, visiting the Subantarctic islands, on December 20, 2015, with suites available from £8,750, including all food and drinks and excursions.
Air New Zealand (www.airnewzealand.co.uk) offers daily flights to Auckland from £1,070 economy return.
For more information about the destination, visit www.newzealand.com/uk