The Kepler Track is probably the one of the New Zealand Great Walks with the easiest access, right out of Te Anau.
Essentially, I walked the Kepler Track in two days, starting out from Kepler car park in the late afternoon after returning back from the Routeburn Track, and camped at the Broad Bay campsite 5 km into the walk. As there are no camping spaces around the Luxmore hut, the next day is necessarily a long one: +1400 meter (very gradual) ascent past the Luxmore hut, continuing over a long ridge (the highlight of the walk), followed by a long descent to the Iris Burn campsite. A total of 24 km and 10 hours of walking.
The next and final day then offered a mellow 22 km through forest to the Rainbow Reach the crossing the Waiau river (one of the Ànduin locations in The Lord of the Rings).
In all honesty, though the Kepler Track it is a fine walk, it does not, in my opinion equal the nearby Milford and Routeburn tracks: While the highlight of the Kepler Track is a fine ridge walk overlooking fiords and with great views, it does not offer the unique New Zealand wildlife and fauna encountered on both Milford and Routeburn Tracks.
The ridge walk.
Itinerary, Kepler Track, camping, Februaru 2015:
Kepler car park-Iris Burn Campsite- Rainbow Reach car park.
Information, bookings (all accommodation incl. tent spaces must be booked in advance) and maps: DOC (Department of Conservation).
Below, the Department of Conservation official video of the Kepler Track: