Fiji comprises c.320 islands, of which some 105 are inhabited. Viti Levu, the largest, constitutes half the land area and is the seat of Suva. The other important islands are Vanua Levu (the second largest), Taveuni, Kadavu, Koro, Gau, and Ovalau. In the group's center is the Koro Sea, east of which is the Lau group. The Yasawa and Mamanuca groups are west of Viti Levu. The larger islands are volcanic and mountainous; the highest peak, Mt. Victoria, or Tomaniivi (4,341 ft/1,323 m), is on Viti Levu, which has the longest river, the Rewa. Fiji's climate is warm and humid. There are dense tropical forests on the windward sides of the islands and grassy plains and clumps of casuarina and pandanus on the leeward sides; mangrove forests are abundant, and hot springs are common in the mountain regions. The chief towns are generally seaports: Suva and Lautoka on Viti Levu; and Levuka, on a small island E of Viti Levu.