The two main airlines Air NZ and Ansett NZ, along with helicopters fly between major cities and resort areas. Both Air NZ and Ansett NZ fly bigger aircrafts whereas Mount Cook is a subsidiary of Air New Zealand and is thus a smaller regional carrier. It links the gateways with the Bay of Islands, Rotorua, Taupo, Nelson, Mount Cook, Queenstown, Wanaka, Te Anau, and Milford Sound.
Domestic flights are pretty expensive.
It is better to look for other better deals, especially during off-peak seasons. By Sea Modern ferries, operated by Interisland Line, travel between Wellington and Picton, connecting the North and South Islands. The ferries not only carry passengers, but also cargo and vehicles. The Interisland crosses Cook Strait several times a day with the journey time of about three hours. Onboard facilities include a cinema, nursery, bars, children's play area, visitor information centers, and a range of food outlets.