This 3000km bike-packing route stretches from the top of New Zealand to the bottom by combining bike trails and back country roads. According to Jonathan Kennett who designed the route, it is composed of " 27% tarmac; 22% gravel road; 31% gravel or limesand cycle trail (1-2 metres wide), 10% tarmac cycle trail, 6% dirt single track, 4% hard beach sand. There are five ferry trips on top of that." The course is described in detail in the third edition of Kennett Brothers book "Classic New Zealand Cycle Trails", which is available from book stores and online from www.kennett.co.nz.
In early 2016 a brevet (self supported ride) was held on the route and it attracted a lot of riders and public interest so is likely to be repeated. The website is here: www.touraotearoa.nz. It has lots of good information and downloadable GPS files of the route. There is a great story with photos about it on the bikepacking website here: www.bikepacking.com/plog/bikepacking-new-zealand-tour-aotearoa/#
Some of the trails described in singletracks.com that make up the route include...
Hauraki Rail Trail, http://www.singletracks.com/bike-trails/hauraki-rail-trail.html
Waikato River Trails, http://www.singletracks.com/bike-trails/waikato-river-trails.html
The Timber Trail, http://www.singletracks.com/bike-trails/whakamaru.html
Old Coach Road, http://www.singletracks.com/bike-trails/old-coach-road.html
Bridge to Nowhere, http://www.singletracks.com/bike-trails/bridge-to-nowhere.html
Rimutaka Trail, http://www.singletracks.com/bike-trails/rimutaka-rail-trail.html
Great Taste Trail, http://www.singletracks.com/bike-trails/great-taste-trail.html
Queenstown Trails, http://www.singletracks.com/bike-trails/queenstown-trail.html
If you like a challenge and love long distance rides you could do a lot worse than Tour Aotearoa.