DOCUMENTS As long as you're staying no more than 31 days (90 days if you're a New Zealand citizen), your valid passport is the only entry permit you need, along with proof of onward journey, the means to support yourself while on the islands and somewhere to stay. And you can sort out the accommodation on arrival.
You can stay for up to five months more, but you'll need to extend your entry permit - at the Department of Immigration in Rarotonga. New Zealanders can apply for a three month extension and other nationals for a month at a time. In both caes, you pay a fee for the privilege. And a reminder...when you leave the country, if you're 12 or older, you'll pay a somewhat extortionate departure tax of NZ$55! (UKĀ£28, US$45, AUS$43, 32 Euros) Approx currency conversion based on rates at 13 July, 2011