In short
Rarotonga is the main island of the Cook Islands, and its geography fits in one sentence: a volcanic mountain, a lagoon, and a single road that circles it in thirty-two kilometres. You cannot get lost.
Avarua is the capital, on the north coast. Muri, to the east, has the finest lagoon and the highest concentration of accommodation. The interior is mountainous, forested and barely inhabited.
Arriving and getting around
The international airport takes flights from Auckland, Sydney and Los Angeles.
The bus network consists of two routes: "clockwise" and "anti-clockwise". They circle the island one way and the other, and that is all — there is nothing else to understand. Scooters and bicycles are hired everywhere.
Aitutaki, whose lagoon is the Cook Islands postcard, requires a forty-five minute domestic flight: it is a separate island, not a day trip from Rarotonga.
What it really costs
The Cook Islands use the New Zealand dollar, with their own local coins.
The island is more affordable than French Polynesia, with a range of guesthouses and small family hotels.
The Punanga Nui market, on Saturday morning in Avarua, is the island's food institution.
When to come
April–November is the dry, cooler season.
December–March is hot, humid and cyclonic.
What nobody tells you
No building exceeds the height of a coconut palm. It is an enforced planning rule, and it is what explains the complete absence of large hotel complexes on the island.
Sunday is given over to worship: many businesses close and activity is reduced. Attending a service for the harmony singing is common and welcomed, provided dress is appropriate.
The cross-island track over Te Rua Manga, the rock needle visible from the north coast, links north to south in three to four hours. The path is steep, slippery after rain, and the southern descent is harder than the climb.
The lagoon is shallow and enclosed: swimming is calm everywhere except near the passes, where outgoing currents are strong. The areas to avoid are marked locally.