variety of boats and yachts on Doubtful Sound for day and overnight cruises. The buses used for these tours are stationed at the Lake Manapouri end of the road. Two tailrace tunnels connect the sound with the lake deep under the mountains north of the pass. The first tunnel was completed in late 1969, a year before the power station became operational, and the second tunnel was built between 1997 and 2002. References Mountain passes of the Southern Alps Landforms of Fiordland