Yes, you must have a valid passport to travel to New Zealand on a cruise ship in 2026, even if you are an Australian citizen. While Australia and New Zealand share a "Trans-Tasman Travel Arrangement," a passport is still the primary document required for identity verification at the border. For international travelers (such as U.S. or UK citizens), the passport must be valid for at least three months beyond your intended departure date. In addition to the passport, almost all cruise passengers must obtain an NZeTA (New Zealand Electronic Travel Authority) before boarding their ship. This electronic permit is mandatory for travelers from "visa-waiver" countries and can take up to 72 hours to process. Cruisers should also be aware of New Zealand's extremely strict biosecurity laws; even if you are only stepping off the ship for a few hours, you must declare any food, plant material, or used hiking gear. Failure to do so can result in an immediate fine of NZD $400. If your cruise is "domestic-only" (starting and ending in NZ), you might only need a government-issued photo ID, but for any itinerary crossing international waters, the passport is non-negotiable.