Kaua?i or Kauai (pronounced /?ka?.a?/ in English and [kou???i] or [k?u???i] in Hawaiian) is the oldest of the main Hawaiian Islands. With an area of 552.3 square miles (1,430.5 km²), it is the fourth largest of the main islands in the Hawaiian archipelago and the 21st largest island in the United States.^[1] Known also as the “Garden Isle”, Kaua?i lies 105 miles (170 kilometers) across the Kaua?i Channel, northwest of O?ahu.