Mount Waiʻaleʻale is a shield volcano and the second highest point on the island of Kauaʻi in the Hawaiian Islands. Its name literally means "rippling water" or "overflowing water".

The mountain, at an elevation of 5,148 feet (1,569 m), averages more than 373 inches (9,500 mm) of rain a year since 1912, with a record 683 inches (17,300 mm) in 1982; its summit is one of the rainiest spots on earth. However, recent reports mention that over the period 1978–2007 the wettest spot in Hawaii is Big Bog on Maui (404 inches or 10,300 mm per year).