Long Island

Although it's 9 km (5½ miles) long and no more than 2 km (1 mile) wide—around 3,000 acres total—this aptly named island has several walking trails through tracts of dense rain forest. Most of the island is national parkland, sheltering birds, butterflies, goannas, and wallabies. Some of its beaches are picturesque; others rocky and windblown. Though its waters are less clear than those off the outer reef islands, there are some excellent snorkeling spots on the island’s fringing reef, where you'll share the balmy water with soft and hard corals, tropical fish, and turtles. You may also see dolphins and migrating humpback whales July through September.