Hanmer Springs
The town is built around hot springs, called Hanmer Springs (http://www.hanmersprings.co.nz). For NZ$18 you can laze in a variety of hot pools, some including smelly sulphur, some filtered which aren't smelly.
There are lots walking trails going through the woods, ranging from flat easy to steep and challenging.
There are three quad biking tour companies in town available, offering trail rides through the spectacular high country landscape.
Hanmer Information point
Mountain biking is very popular with a great variety of tracks available to purchase from the Hanmer Information point (http://www.hanmernz.com).