Southwest of Queenstown and north of Te Anau in Fiordland National Park, the popular Milford Track is a 53.5km hut-to-hut trek through thick beech forest and remote mossy gorges. It passes numerous cascades, including the 600m Sutherland Falls, and ends at Milford Sound shadowed by 1,000m glacial carved cliffs. The route typically takes about 4 days (3 nights).
It starts in Glade House on the northern edge of Lake Te Anau, and ends on the shores of Milford Sound. Along the way, the route crosses the Clinton River, passes through dense beech forest, ascends MacKinnon Pass (1,100m), and winds through fern-carpeted rainforest.
Since you will be tramping with the other 14,000 annual hikers, camping is not permitted and you must stick to your reserved itinerary and hut reservations. Permitting starts July 14th for the following calender year. A maximum of 40 hikers a day are allowed to start the Milford Track. Also, both trailheads are only accessible via ferry boat.
The route ends at the Sandfly Point ferry dock on Milford Sound. Make sure you purchase your ferry ticket before setting out in Te Anau (confirmed at least a week before), and do not miss the last ferry (about 3pm) or you will spend a fly infested evening waiting for the next mornings ferry.
Note: You can expect a rooty, rocky track with a steep ascent and descent of MacKinnon Pass. Plus, be prepared to be wet the entire trip. There are unbridged streams up to 1m deep.
Overall, Milford Track is the 1st most popular hiking trail of all 15 hikes in New Zealand.