Kauai is an island in the Central Pacific, part of the Hawaiian archipelago. It is the oldest of the Hawaiian Islands — having formed about 5 million years ago — and is also the fourth largest, with an area of 562 square miles (1,456 square kilometers). Rainforests and mountain ranges cover more than 90% of Kauai, earning it the nickname “the Garden Isle.” It is home to about 72,000 people.