Extract: A diver's guide to Milford Sound

Milford Sound (Piopiotahi) is a primeval, prehistoric place. Sharp, teethlike granite mountains rise 5,551 feet (1,692 m) directly from the ocean floor, neck-craners and jaw-droppers, framing a fjord holding oily-looking jade green water.

Tucked away in the southwest corner of New Zealand’s South Island, Milford Sound is part of Fiordland National Park, New Zealand’s largest national park (2.9 million acres/1.2 million ha), a wild area in the heart of Te Wāhipounamu- South West New Zealand, a Unesco World Heritage site.

It rains 25 feet (7.6 m) a year here, and that rainfall is the key ingredient in the amplified alchemy of this otherworldly landscape. It’s critical to the lush flora that stubbornly clings to impossibly steep rock faces coursing with silver threads of waterfalls. It’s also critical to the bizarre marine life.

The rain strips tannins from the soil, layering tinted freshwater 30 feet (9 m) thick on the fjord’s saltwater, choking off light, tricking creatures of the deep into thinking they’re in hundreds of feet of water when they’re actually in 50 feet (15 m).

This area is home to the Milford Track, a 32-mile (53.5 km) trail known as the Finest Walk in the World. It is also a popular destination for day trips and overnight cruises. For divers, Milford Sound is somewhat of a fond secret. This marine reserve is off the beaten recreational dive track, but beloved by those in the know. It is a unique area, filled with life (from black coral forests to sevengill sharks to Fiordland crested penguins), making for unforgettable diving.

Milford Sound stretches roughly 10 miles (16 km) from Freshwater Basin to the Tasman Sea. It’s actually a fjord, rather than a sound (having been carved by glaciers, not rivers), that is nearly two miles (3 km) across at its widest point. The fjord runs more than 882 feet (269 m) deep, hemmed in by jagged peaks that are still being born. The Alpine Fault, one of the world’s major plate boundary faults, crosses the mouth of Milford Sound, shifting around two to three centimetres every year.

This is the wettest inhabited place in New Zealand, and one of the wettest on Earth. It rains an average of 182 days per year, which keeps the towering Lady Bowen Falls (531 feet/162 m), one of Milford’s two permanent waterfalls, in business. Milford Sound is located at the end of an adventurous road that winds through the Eglinton Valley (a golden tussock carpet flanked by mountains) before siphoning vehicles through the Homer Tunnel, a 0.8-mile (1.3 km) wormhole hewed largely by hand from solid granite.

(Tip: You might be lucky enough to spot kea en route. These intelligent birds are the only alpine parrots in the world, with brilliant orange colouring under their wings and curved beaks. You may catch them calmly dismantling your car or removing anything left unattended; do not feed them.)

There is plenty of hiking in this area, which is as hard as you want it to be. (Bear in mind that help can be difficult to come by in this remote place.) Day cruises are also popular and efficient ways to explore Milford Sound, like Southern Discoveries’ Encounter Nature Cruise on the Lady Bowen. This two- to three-hour trip takes place on one of the smaller boats running in the area, with an indoor seated area, outdoor viewing deck, and café serving up warming soup, coffee, and sandwiches (bring cash).

On board, we slowly cruise out into the sound, pausing to admire some snoozing New Zealand fur seals, or to crane our necks at waterfalls that seem to descend from the sky itself. During the trip, we learn about the area’s flora and fauna, history and legends, some of which go hand in hand–sandflies, for example, the blight on this otherwise brilliant location, were dubbed the "most mischievous animal” by Captain Cook in 1773. According to Māori legend, the underworld goddess Hine-nui-te-pō was fearful humans would not want to leave the paradise of Fiordland so she created sandflies as a most effective reminder that we shouldn’t linger too long.

Hine-nui-te-pō was wise to be worried: Milford Sound has long cast a spell over travellers. Tourism was already booming here back in the 1890s as legend of the region’s wild beauty attracted walkers by the droves. Before the 2020 pandemic, Milford Sound was reaching critical mass: 500,000 visitors in 2012 soared to more than 900,000 in 2018, 90% of whom came from overseas. (Many Kiwis haven’t been to Milford, deeming it “too touristy.”)

The combination of Milford’s remote location, coupled with its fragile ecosystem, means that something needs to give. There was a plan: Back in 2007, the Fiordland National Park management proposed capping the daily limit of tourists to 4,000, but that was never enforced. At the time of writing, restricting visitor numbers is being reconsidered, but that approach isn’t popular with everyone. And therein lies the rub: weighing the incalculable benefits of travel against its very real cost. There is no easy answer, no silver-bullet solution.

The day cruise wraps up with two special activities: a 45-minute kayak, gently paddling around protected Harrison Cove, before visiting the Underwater Observatory. This is New Zealand’s only floating underwater observatory, a circular viewing room located 33 feet (10 m) below the surface, giving non-divers a literal window into the area’s deepwater emergence in action: the tannin-rich layer of freshwater convincing darkloving marine life to thrive near the surface.

And this is why Milford Sound is so special to divers. Divers descend through the cold and disorienting cloud of freshwater to reach the warmer, clearer saltwater below, revealing gently sloping rock reefs and walls. The walls are carpeted in yellow zoanthids and bright red coral, a protected species that can be found around 59 feet (18 m). In some areas, the walls plunge downward beyond sight–one reason why this relatively unexplored area is so attractive to tech divers.

On our first dive, we followed a wall with an abundance of nudibranchs, sponges, and gorgonians. More than 150 species of fish can be found here, and we shared the water with schooling kingfish, blue cod, girdled wrasse, and spiny dogfish. A New Zealand fur seal and a couple of sevengill sharks also turned up to have a look at us.

Our second dive was deeper, with more spiny dogfish and large crayfish (Kiwi-speak for rock lobster). We also explored the area’s black coral forests, a deep-sea coral usually found at depths below 262.5 feet (80 m). Here, it can be found at 26 feet (8 m). Fiordland is believed to have the world’s highest concentration of black coral trees, which have feathery white branches and are often wrapped in striped snake stars. (These echinoderms have a symbiotic relationship with the coral.) Black coral grows very slowly (around 1 to 2 cm per year), and the colonies here are believed to be hundreds of years old, reaching heights of 16.4 feet (5 m).

This area is a marine reserve, established in 1993. Dive sites (which don’t have names) are chosen based on what the weather is doing. Most days are two dives, kept on the shallow side (82 ft/25 m) due to the high-altitude road. A hot drink and snacks are ready and waiting on the boat between dives. (Sometimes the surface interval includes a short walk to a secluded waterfall, as well.)

Do not leave Milford Sound without embarking on an overnight cruise, like Real Journeys’ Milford Mariner or sister ship Milford Wanderer. Designed to replicate traditional trading scows, these voyages depart around 4.30pm, cruising the sound with weather-dependent activities on offer (kayaking, a tender boat cruise, even swimming) before mooring up in Harrison Cove for the evening.

After a delicious buffet dinner, the stars pop out in a sky free from light pollution and the sound settles down to sleep. Even more spectacular is the quiet of the morning, like dawn crowning the very first day, waking up to a still beauty and all the promise morning and this remarkable place bring.