Mount Waialeale

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

The mountain, at an elevation of 5148 ft, averages more than 373 in of rain a year since 1912, with a record 683 in 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 in per year).

Climate and rainfall statistics
The summit of Waialeale features a tropical rainforest climate (Köppen Af), with substantial rainfall throughout the course of the year. quotes 11684 mm per year figure as being the 1912–45 average, an average that quite possibly will have changed since then, while The National Climatic Data Center quotes this figure as a 30-year average. The Weather Network and The Guinness Book of Weather Records quotes 11455 mm rain per year, while  quotes 11680 mm as the average annual rainfall at Mount Waialeale and  claims 13,000 mm falls here. Similarly, The Weather Network and the Guinness Book of Weather Records quote 335 days with rain here while suggests that rain falls on 360 days per year.

The local tourist industry of Kauai has promoted it as one of the wettest places on earth, which it is. The rainfall at Waiʻaleʻale is evenly distributed through the year.

Causes
Several factors give the summit of Waialeale more potential to create precipitation than the rest of the island chain:
 * 1) Its northern position relative to the main Hawaiian Islands provides more exposure to frontal systems that bring rain during the winter.
 * 2) Its peak lies just below the so-called trade wind inversion layer of 6000 ft, above which trade-wind-produced clouds cannot rise.
 * 3) The summit plateau is flanked by steep walled valleys over 3000 ft deep on the three sides most consistently exposed to moisture bearing weather systems. These serve to funnel and concentrate any available precipitable water directly towards the mountain.
 * 4) The steep cliffs of the mountain's flanks generate intense orographic lift, causing the moisture-laden air to rise rapidly – over 4000 ft in less than 0.5 mi – This combined with the 'barrier' of the trade-wind inversion, serves to very efficiently squeeze almost all of the moisture out of the incoming clouds directly over and immediately downwind of the peak.

Ecology
The great rainfall in the area produces the Alakai Wilderness Preserve, a large boggy area that is home to many rare plants. The ground is so wet that although trails exist, access by foot to the Waiʻaleʻale area is extremely difficult.

A number of rare local plant species are named for this mountain, including Astelia waialealae, Melicope waialealae, and the endemic Dubautia waialealae.