Doubtful Sound

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.

Ask Dawn about a day or overnight tour to Doubtful Sound.