A map of the area with Lake Manapouri in the bottom right and Doubtful Sound top left.
At the town of Manapouri in Pearl Harbour, we boarded a high speed catamaran for the 50 minute trip across Lake Manapouri. A bit cool on the upper deck in the early morning but some good views of the surrounding mountains.
The boat docked adjacent to the Manapouri Hydroelectric Plant. This is a major power plant on the NZ grid and was built to supply an aluminum smelter located in Bluff. Construction took place in the 1960's. It uses the 160 m differential between Lake Manapouri and Doubtful Sound to generate 800 MW of energy. An interesting fact was that they made an error in the original design of the tailrace tunnel which is 10 km long. It was an unlined tunnel constructed with drill and blast technique. They neglected to factor in the roughness of the surface of the tunnel and when the plant went into service, the additional friction caused back pressure on the turbine which limited the output to around 70% of design. This was rectified with the installation of a second tailrace tunnel constructed using a tunnel boring machine (similar to the SAB tunnel 3) in the 1990's. Usually our tour included a plant visit but it was unavailable because they are in the midst of major plant maintenance. Oh well! Seen lots of underground plants before.
From the boat dock, we boarded a bus that took us to Doubtful Sound using the 21 km Wilmot Pass construction road that was built to bring in the major equipment for the plant from Doubtful Sound where it was delivered by barge. Apparently the most expensive road ever built in NZ at $2/cm.
When we arrived at Doubtful Sound, we boarded another beautiful catamaran. There were three decks with two indoor lounges. You know why they have the indoor decks once you learn that it rains here more than 200 days a year with a total annual rainfall of 8,000 mm. The 2600 hp pushed us at a cruising speed of 22 kts.
Doubtful Sound was named 'Doubtful Harbour' in 1770 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, although it is not technically a sound but a fiord. Even though it was a bit overcast, it was beautiful.
The boat tour was three hours and took us out to the Tasman Sea where we saw some more fur seals.
There are several continuous waterfalls including the 836 m Browne Falls.
We travelled down a couple of the arms taking in the scenery.
We retraced the journey back to Te Anau and were "home" by 4:00 pm in time to walk down the street to "The Moose" for a drink and snack.
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