Fiji is an archipelagic nation in Melanesia, part of Oceania in the South Pacific. It consists of more than 330 islands, of which about 110 are permanently inhabited. The two largest islands, Viti Levu and Vanua Levu, contain about 87% of the total population. Suva, the capital, is located on Viti Levu. Most of the islands were formed through volcanic activity starting around 150 million years ago, and even today, some geothermal activity persists. The terrain is mostly mountainous, covered with thick tropical forests. Fiji's geography also includes extensive coral reef systems, such as the Great Sea Reef, the third-longest barrier reef in the world. The climate is tropical maritime and warm year-round. Fiji is a major tourist destination and is also known for its exports of sugar, gold, and bottled mineral water.