Twin Stream is well known for its rock climbing walls but in winter it has some good and steep lines to be skied.
You can either walk in or fly in; about 4 hours walking vs 5 minutes flying: $0 vs $350 a load. Contact Heliline Glentanner at 0800 650 651 and make sure you ask for a quote including GST, landing fees and whatever else fees apply, they tend to forget to mention it in the quote.
We explored the north side of the valley. There is an old moraine wall that gives safe access to the upper mountain. Large run out avalanches are pretty visible at the bottom.
The tour is pretty straight forward and takes you to the saddle to Kai Tarau at 2350m.
An axe and some crampons are suggested as you will be travelling in glacier terrain.
On the southern aspects of the valley there is plenty more to explore and a bivi site is available at the bottom of the rock face at 1350m.
The walk out is a good mix of boulder hopping and matagauri; about 3 hours to the car park.
You need to contact Glentanner station for permission at 435-1843.