Oceania, the smallest of the continents, is usually defined as consisting of Australia, New Zealand, New Guinea and the thousands of islands and atolls that are scattered across the Pacific Ocean. Australia's largest cities lie on the coasts; the interior or outback is dry and barren. Sydney is famous for its picturesque harbour and bridge. Off the coast lies the Great Barrier Reef. To the north, New Guinea is covered with dense rain forest. New Zealand has spectacular mountain and coastal scenery, and a temperate climate. The island chains of Micronesia, Melanesia and Polynesia offer the blue seas, white sandsand swaying palms that are everyone's idea of a South Sea paradise.