The Twizel Department of Conservation have pamphlets with all the DOC walks in the area – there are plenty!
You can go sky diving on the outskirts of Twizel or try some heli-mountain biking.
Down in Omarama you can experience gliding. The world gliding championships were hosted there in 1995.
Alan Campbell Fly Fishing Services
+64 3 435 0088
PO Box 21
Alans website: http://www.flyfishinguide.co.nz