Mānā is a coastal plain with an ancient sea cliff at its inner edge, which extends from Waimea in the south to the north on the western shores of Kauai. Throughout prehistory, large areas of the Mānā Plain were covered by the great Mānā wetlands, allowing native Hawaiians to canoe as far south as Waimea.
After the arrival of Europeans to the island, the wetlands were drained for cultivation of sugar cane and rice. One of the first European settlers, Valdemar Knudsen, drained a portion of the Mānā wetlands by excavating a ditch through to the ocean at Waiele. The first sugarcane was planted in Kekaha in 1878. The area is now home to farmers and a military facility (Pacific Missile Range Facility (PMRF.))