Avarua Town on the north coast, minutes from the international airport, is the administration centre of the Cook Islands. Most people end up in town for a shopping trip or part of a bus trip around and it's a nice place to spend a few hours, especially on Saturday morning when the open air market takes place. You'll find everything from brightly coloured sarongs (wrap around dresses), to flower garlands, fresh fish and tropical fruits.
Avarua town is very small and takes only a few minutes to walk the length of its main high street. There's a supermarket, two banks both with ATM machines, several restaurants / cafes, internet booths and several good boutique shops specialising in the sale of black pearls and fine handicrafts. There are also a few budget places to stay in town but without a beach and mostly located in the hills it's not the best option for a holiday.
There are two harbours in Avarua. Head to Avatiu on the west side of town for large cargo boats heading to the outer islands or for yachts visiting from overrseas. If you are looking for a game fishing charter or small boat to take you sightseeing then the harbour in the town centre is the one.
Nightlife in Avarua Town is pretty good and there are even a couple of night tours that gho bar hopping around the best spots. There's a cinema too showing the latest blockbusters in case the weather turns on you.
The coast along Avarua Town is rocky but a passage through the reef makes it ideal as a harbour for fishing boats and yachts (yachting season May-Sep). There are a few interesting buildings to see, notably the Cook islands Christian Church, the adjacent palace of the ancient kings and the more modern museum, all to the east of the main shopping area.
There are a few part-sandy beaches to the east of Avarua Town but swimming is restrictive. Heading east from town you'll get stunning views of mountains from the main road and you'll find some ancient stone foundations (marae) on the inland road, as well as several dirt tracks leading into valleys.