The river's source is the Alaka'i Swamp, the largest high-elevation swamp in the world, located in Kauai's central highlands. Waimea flows south, passing through the breathtaking 3,000-foot-deep (910 m) Waimea Canyon, dubbed as the "Grand Canyon of the Pacific."
The valleys of the Waimea River and its tributary, the Makaweli River, were once heavily populated. It enters the Pacific Ocean at Waimea, near the 1778 landing place of Captain Cook on Kauai.
Every winter, high surf dams the mouth of the Waimea River with sand, and the heavy rains flood the valley. During this period, local surfers dig out a channel allowing high volume of water to flow to the ocean, creating standing waves perfect for river surfing.