This is a challenging ride on a hiking track through Mount Richmond Forest Park. It is best ridden south to north. There are two huts on the trail so some people spread the ride over two days. It's an historic gold mining area with some heritage interest. You'll climb and descend about 1000 metres over the 35km as you cross over the Richmond Range. Don't attempt it in the wet as expert skills are needed even when conditions are dry. You will be riding through Beech forest for much of the way. It's quite a popular ride for those who like more natural trails and an epic challenge.
To avoid the hassle of a shuttle you can ride a nice chunk of it as an out-and-back ride from the south end up to Fosters Hut. That ride will only need intermediate skills and is about 14kms long.
There is more information on the Department of Conservation website here: http://www.doc.govt.nz/parks-and-recreation/places-to-go/marlborough/places/mount-richmond-forest-park/things-to-do/tracks/wakamarina-track/