As on Moorea and Bora Bora, one of the most enjoyable ways to see the island is on a lagoon excursion that includes snorkeling and a picnic on an islet out on the reef. The biggest difference here is that with relatively few tourists around, you and your companions are likely to have the islet all to yourselves.
The all-day excursion with Huahine Nautique (tel. 68.83.15; www.huahine-nautique.com) takes you by outrigger canoe through Maroe Bay and around Huahine Iti. You'll stop for snorkeling and a picnic featuring freshly made poisson cru, and you will observe shark-feeding before returning to Fare. Huahine Nautique's canoes have shade canopies, and the guides speak English as well as French. Poetaina Cruises (tel. 60.60.06) also does all-day trips, but I can't guarantee that you'll have shade on your outrigger. Don't be surprised if you visit Huahine Nui Pearls & Pottery. The excursions cost about 8,500CFP (US$106/£54) per person.
As on most of the Society Islands, you can make four-wheel-drive expeditions into the mountains here. You will see a bit of the interior of Huahine Nui with Paul Atallah on his Island Eco Tours, which I would take first. You will repeat seeing the Maeva maraes, but either Huahine Land (tel. 68.89.21), which is owned by American expatriate Joel House, or Huahine Explorer (tel. 68.87.33) will also take you to Huahine Iti on its half-day expeditions. Both charge about 5,100CFP (US$64/£32) per person.
Note: This information was accurate when it was published, but can change without notice. Please be sure to confirm all rates and details directly with the companies in question before planning your trip.