Coast to Coast - Dunedin to Milford Sound - How?

Hey, cool idea. If I was you I would start out here: http://www.topomap.co.nz and then http://www.doc.govt.nz/parks-and-recreation/tracks-and-walks/ Once you get to Clyde via the Rail Trail you can head to Cromwell via the Leaning Rock and Mt Horn. Then Cromwell to Arrowtown via the hills North of the Kawarau Gorge. Then down to Queenstown. Then maybe catch the ferry across the lake to Walter Peak and follow the tracks along the West side of Lake Wakatipu to the Greenstone. Go up the Greenstone to the Divide. Then somehow on to Milford Sound... either via the road or go South to the start of the Milford Track and follow that to Milford Sound? It will be an epic trek whatever route you go with!

3k appx north of Cromwell..Lowburn Valley Rd..2k right into Swann Rd..2k left onto DOC access to Pisa Conservation Area and the Cromwell - Cardrona Pack Track. Above Meg hut is Touhy saddle and a route over Queensbury Hill and Mt.Allen to the Crown Range Rd. All downhill to Arrowtown by road or over Mt.Scott and Crown Pk (Glencoe Stn i believe). The Arrow river gives access to Big Hill and Brow Pk and over to Coronet Pk where you could walk down to Arthurs Point. The Moonlight trail goes around the back of QT and Ben Lommond.