The Great Walks are booked in advance, and the huts are the way to sleep

New Zealand's Great Walks (Milford, Routeburn, Tongariro Northern Circuit, Abel Tasman) use a hut and campsite booking system that opens months ahead and sells out for the summer within hours for Milford; book the day bookings open. Day hikes don't need bookings: the Tongariro Alpine Crossing (shuttle required), the Hooker Valley track at Mount Cook, and Roys Peak near Wanaka. Weather in the mountains changes fast; check the forecast at the DOC visitor center.