Kauai is 550 square miles. It's twice the size of the Superstition Wilderness, and fits nicely inside Loop 101 if overlayed on a map of Phoenix. The center of the island is often regarded as the wettest spot on Earth, averaging over 450 inches of rain a year. Less than 20 miles away, the west coast of the island is like Phoenix, with an average of about 8 inches a year.