Doubtful Sound

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Typical view of the Doubtful Sound.

Location of Doubtful Sound on the South Island of New Zealand.

Doubtful Sound is a fjord on the south west corner of New Zealand, close to the smaller but more accessible Milford Sound. The steep hills are known for their hundreds of waterfalls during the rainy season. This fiord is home to one of the southernmost population of bottlenose dolphins. This population is small (56 individuals) and has been drastically declining over the past 6 years. It is common for tour boats to interact with these dolphins.

Doubtful Sound was named 'Doubtful Harbour' by Captain Cook, who did not enter the inlet as he was uncertain whether it was navigable under sail. It was later renamed Doubtful Sound by whalers and sealers.

Access to the sound is either by sea, or by the Wilmot Pass road from the Manapouri Power Station. Most areas of the sound itself are only accessible by sea however, as the road network in this area of New Zealand is sparse or nonexistant, as is the human population.

There are three distinct arms to the sound, which is the site of several large waterfalls, notably Helena Falls at Deep Cove, and the Browne Falls which have a fall of over 600 metres.

Doubtful Sound is unusual in that it contains two distinct layers of water that do not mix. The top few meters is fresh water, fed from the high inflows from the surrounding mountains. Below this is a layer of cold, heavy, saline water from the sea. The difference in Refractive index between these two layers makes it difficult for light to penetrate. Thus, many deep-sea species, such as Black coral will grow in the comparatively shallow depths of the Sound.

Charles John Lyttelton, 10th Viscount Cobham, Governor-General of New Zealand (1957-1962) writes about this part of Fiordland:

"There are just a few areas left in the world where no human has ever set foot. That one of them should be in a country so civilized and so advanced as New Zealand may seem incredible, unless one has visited the south-west corner of the South Island. Jagged razor backed mountains rear their heads into the sky. More than 200 days of rain a year ensure not a tree branch is left bare and brown, moss and epiphytes drape every nook. The forest is intensely green. This is big country... one day peaceful, a study in green and blue, the next melancholy and misty, with low cloud veiling the tops... an awesome place, with its granite precipices, its hanging valleys, its earthquake faults and its thundering cascades."

[edit] Deep Cove

Deep Cove ( 45°27′S, 167°09′E), an arm of Doubtful Sound, is the site of discharge of water from the Manapouri Power Station tailrace tunnels. Deep Cove, like the rest of Fiordland is a unique and pristine environment. The discharge has had an impact, although this is an area naturally high in fresh water inflows (7.6 metres of rain annually).

[edit] Wildlife

Wildlife to be found in Doubtful Sound include:

Fur seals
Bottlenose dolphins
Penguins (Fiordland crested and blue)

The waters of Doubtful Sound are home to abundant sea creatures, including many species of fish, starfish, sea anemones and corals. It is perhaps best known for its Black coral trees which occur in unusually shallow water for what is normally a deep water species.