Almost all the way in the south, we decided to do excursions by bus due to our limited travel time.
We took the bus from Invercargill to Te Anau where we stayed for three nights in a backpackers. From there we did two day trips to the fjords.
On the first day, Doubtful Sound was on the agenda. In front of our accommodation we were picked up by bus and brought to the harbor of Manapouri where we boarded a catamaran after a short wait. On this we enjoyed a one hour trip across Lake Manapouri to the end of the West Arm. At this place there is an underground hydroelectric power plant which we visited afterwards. Since we had already seen such plants in Switzerland, this was not extremely spectacular for us.
After the tour of the power plant, we were again taken by bus to Doubtful Sound where another, somewhat larger catamaran was waiting for us. With this catamaran we were shown parts of Doubtful Sound during three hours. Fortunately, the weather improved in the afternoon so that the rain let up and the stay on deck was no longer a test for our windstopper jackets :-)
In the evening we went back the same way (without detour through the power plant).

On the second day we were picked up again by a bus and brought to Milford Sound. On the way there we drove through the one kilometer long Homer Tunnel. Since this single lane tunnel is so remote the traffic lights and street lights are powered by a diesel powered generator. From the harbor we took a boat through the smaller Milford Sound to the sea and back. In the ship we were addressed by a family whether we were the tandem riders which you had seen some days ago in Oamaru. It was us, there are not so many :-)
Unfortunately the weather was much worse compared to the day before. It rained a few centimeters of the 4-6 meters of precipitation per year. For this we got to see dolphins on the trip.

In summary, we liked the Doubtful Sound tour much better than the one at Milford Sound. This was not only due to the weather, because the Doubtful Sound tour was somehow more "personal" and familiar. Possibly this is also due to the fact that on Doubtful Sound there were about two other boats besides the catamaran, whereas on Milford Sound the tour boats had to queue up in front of the attractions.

Now we are glad soon again with the tandem individually to pedal to be able and not with the masses by bus and boat like cattle through the area to be freighted. The tours were a great experience, but this way of traveling just doesn't suit us as well as traveling by tandem.