Avarua, the capital of the Cook Islands, is situated on the northern coast of Rarotonga -- just a 15-minute walk from the tender dock. In town you'll find a post office, banks, souvenir and craft shops, and jewelry stores carrying the region's ubiquitous black pearls, restaurants and supermarkets.
On Saturdays, the Punanganui Market in Avarua is a bargain-hunter's dream with arts and crafts, clothing, and fresh fruits and vegetables; it's also a good place to sample local cuisine like coconut rolls and ika mata (marinated raw fish).
Muri Beach is Rarotonga's prettiest and busiest stretch of sand, sweeping in a small arch for over half a mile along the island's southeast coast. There's a shallow lagoon for swimming and snorkeling, and many areas are protected marine reserves -- which means fish are plentiful.
There are guided safaris and hikes for all levels of fitness through the rainforest, noni plantations and bird sanctuaries -- and to Wigmore's Waterfall and the base of the Needle, the highest point on the island near its center. Pa's, a local operator, offers mountain and nature tours on Tuesdays and Thursdays.
Though the lagoon itself is shallow, there are great scuba spots just off the reef: wreck dives, walls, drop offs, canyons, coral gardens and an abundance of fish life (and whales, turtles and rays). Because calls do get canceled from time to time, we recommend booking through your ship's excursion department; however, there are local operators offering dives, including Dive Rarotonga and Cook Islands Divers.
For duffers, there's a nine-hole golf course at the Rarotongan Golf Club. The club is open from 8 a.m. daily (closed Sundays); you can hire a half set of clubs.
If you'd like to learn more about Cook Islands history and culture, visit Cook Islands Cultural Village on Rarotonga. There are nine thatched huts, each devoted to a different aspect of island life, including handicrafts, fire making, coconut husking and traditional medicine.