Deep Cove () is an arm of Doubtful Sound, a deep indentation in the southwest coast of

New Zealand New Zealand ( mi, Aotearoa ) is an island country in the southwestern Pacific Ocean. It consists of two main landmasses—the North Island () and the South Island ()—and over 700 smaller islands. It is the sixth-largest island count ...

's South Island. Along with the Hall Arm, which lies to the southwest of Deep Cove, it forms one of the two most remote parts of the sound from the

Tasman Sea The Tasman Sea ( Māori: ''Te Tai-o-Rēhua'', ) is a marginal sea of the South Pacific Ocean, situated between Australia and New Zealand. It measures about across and about from north to south. The sea was named after the Dutch explorer ...

, with its mouth being from the mouth of Doubtful Sound. Elizabeth Island lies close to the junction of Deep Cove and the Hall Arm. Deep Cove by itself is about four kilometres long and is home to several waterfalls, including Helena Falls and Lady Alice Falls. Until the 1960s, Deep Cove was only accessible from the sea or via the

Wilmot Pass The Wilmot Pass is a high pass on the main divide of New Zealand's South Island. It connects Doubtful Sound, a deep indentation in the coast of Fiordland, to the valley of the West Arm of Lake Manapouri. The pass is named after E. H. Wilmot, a ...

walking track. In 1964, however, the cove saw the start of considerable activity as it became an important part of the Manapouri Hydroelectricity Project as the site of the tailrace tunnel from

Lake Manapouri Lake Manapouri is located in the South Island of New Zealand. The lake is situated within the Fiordland National Park and the wider region of Te Wahipounamu South West New Zealand World Heritage Area. Māori History According to Māori legend ...

. A tunnel connects the cove with the lake. The tunnel was completed in late 1969, with the power station became operational the following year. A second tunnel was started in 1997 and became operational in 2002. The discharge of clear fresh water has affected

fauna Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is ''flora'', and for fungi, it is ''funga''. Flora, fauna, funga and other forms of life are collectively referred to as ''Biota (ecology ...

and

flora Flora is all the plant life present in a particular region or time, generally the naturally occurring (indigenous (ecology), indigenous) native plant, native plants. Sometimes bacteria and fungi are also referred to as flora, as in the terms '' ...

by letting light into the lower layers of the sound. Nevertheless, this is an area naturally high in fresh water inflows (7.6 metres of rain falls annually). In the 1980s an application was made to extract and ship the water overseas but the project did not proceed. The strong salinity stratification generated by the freshwater layer has been the focus of a number of oceanographic expeditions using the cove as a natural laboratory. The research found that the riverine nature of the inflow gradually dissipated over a few km but that the underside of the freshwater plume sustains some of the sharpest stratification ever observed. The measurements detected

internal wave Internal waves are gravity waves that oscillate within a fluid medium, rather than on its surface. To exist, the fluid must be stratified: the density must change (continuously or discontinuously) with depth/height due to changes, for example, in ...

motion both from the nearby river inlet and from the ocean 40 km away. Deep Cove Buoy

Today, Deep Cove serves as the starting point for Doubtful Sound cruises on tour boats stationed at a small wharf in Wanganella Cove, within Deep Cove. The full-day tours depart from

Manapouri Manapouri is a small town in Southland / Fiordland, in the southwest corner of the South Island, in New Zealand. The township is the westernmost municipality in New Zealand. Located at the edge of the Fiordland National Park, on the eastern ...

by boat to travel across

, followed by a bus ride over Wilmot Pass, and return the same way after the boat tour in Doubtful Sound. The wharf in Deep Cove is also used for unloading large components such as transformers from barges, to be delivered to the Manapouri Power Station via Wilmot Pass, as there is no other road access to the power plant and these components would be too large to ferry across Lake Manapouri from the other side.

Vegetation and wildlife

The wildlife in this area include dolphins and birds. Introduced species include mice, rats and hare. The Deep Cove watershed is heavily forested with ''

Nothofagus ''Nothofagus'', also known as the southern beeches, is a genus of 43 species of trees and shrubs native to the Southern Hemisphere in southern South America (Chile, Argentina) and Australasia (east and southeast Australia, New Zealand, New Gui ...

'' (beech) trees, a large variety of understory shrubs and ferns being present.

References

{{reflist Bays of Southland, New Zealand Landforms of Fiordland Sounds of Fiordland