NZeTA and visitor levy. Most visitors from visa-waiver countries, including the US and UK, need a New Zealand Electronic Travel Authority (NZeTA) before boarding and pay the International Visitor Conservation and Tourism Levy (IVL) with it. Australian citizens do not need one; check the visa rules for your passport before you fly.
Biosecurity declaration. Every traveler, children included, completes New Zealand's digital arrival declaration (NZTD), which can be submitted up to 24 hours before departure. Declare all food and used outdoor gear such as hiking boots, tents and fishing equipment, or use the amnesty bins before biosecurity.
Overnight closure. The terminal closes from 1:30 to 3:00 every night, so travelers on very late arrivals or early departures cannot wait inside during those hours.
Ferry check-in. The Interislander and Bluebridge ferries sail from separate terminals, so give the operator and sailing time when you book; ferry companies set their own check-in deadlines, especially for vehicles.