Wanaka is a small town 110 km from Queenstown and the lake of the same name is one of the loveliest and biggest in New Zealand. It is fed by glacial melt off and because of this its color is spectacular. It borders Mount Aspiring, the second highest mountain in New Zealand at 3027 m.
In Queenstown you can take a boat for a cruise on the Lake, it is a bit expensive, $ 48, about 24 euros, I did it to see the view from inside the lake which are spectacular, you will have a good time especially if the weather is good, the boat is old, and symbolically usually whistle when approaching back to port
About 40 km from Wanaka, on the road leading to Mount Aspiring National Park, you can find this small, beautiful lake. It is famous for having good reflections, but the truth is that most of the lake is covered by vegetation. Getting to the lake from parking takes about 20 minutes, go around about another 15, and it's definitely worth going up to a viewpoint, this can take about 40 minutes round trip.