Mount Waialeale (or Wai'ale'ale) is a volcanic crater and the second highest point on the island of Kauai in the Hawaiian Islands. In the Hawaiian language, Wai'ale'ale means “rippling water” or “overflowing water.” Averaging more than 452 inches (11,500 mm) of rain a year since 1912, with a record 683 inches (17,300 mm) in 1982, its summit is one of the wettest spots on earth. As this rainwater makes its way down the 5,148-feet tall peak, they form innumerable streams. One spot on Mt. Waialeale is called the “Wall of Tears” because there are so many waterfalls plummeting down the deep, tropical green sides of the mountain that it looks as if it is crying.
Mount Waialeale isn’t easily accessible on foot. The sides are near vertical and ground is covered with trees and plants with a thick undergrowth of ferns. There are a few hiking trails in the area. The only way to really see the Wall of Tears is by helicopter, and even then you have to get lucky since the area is usually shrouded with clouds.
There are several reasons why Wai'ale'ale receives so much rain. First, Kauai is the northernmost of the main Hawaiian Islands, so it has more exposure to frontal systems that bring rain in the winter. Second, Wai'ale'ale has a round and conical shape, which exposes all sides of its summit to moisture-laden winds. Third, its summit lies just below the trade wind inversion layer of 6,000 feet (1,829 m), above which trade-wind-generated clouds cannot rise. And finally, the mountain's steep cliffs cause the humid air to rise quickly over 3,000 feet (910 m) in less than a half mile (800 m) and drop a large portion of its rain on one spot.
The summit itself is rather barren, despite all the water it receives. One of the reasons for that is that few plants and trees can handle that much rain. Also, since the summit is shrouded in clouds on most days of the year, little sunshine reaches the ground to foster plant growth. However, fungi and lichen flourish here.