Finland is one of the countries whose citizens are eligible for the New Zealand visa waiver program. This means that Finnish citizens can enter New Zealand for tourism, business, or transit purposes for up to 3 months without needing to apply for a visa in advance. However, they will still need to obtain an Electronic Travel Authority (ETA) prior to travel, which can be easily applied for online.
If a Finnish citizen wishes to stay in New Zealand for longer than 3 months, or for other purposes such as work or study, they will need to apply for an appropriate visa in advance. The New Zealand immigration website provides detailed information on the different types of visas available and the application process.