Wailua River, river, Kauai island, Hawaii, U.S. It flows from the slopes of Mount Waialeale about 10 miles (16 km) inland to the east-central coast. At the southern end of the river is Wailua Falls, which drops 200 feet (60 metres). The nearly 1,100-acre (450-hectare) Wailua River State Park, situated along the river, is rich in Hawaiian tradition. The first migratory Tahitians, including the great chief Puna-nui, arrived in the 12th century and settled near the present coastal towns of Wailua and Kapaa. During the period of island kings, only royalty (alii) could visit the area. The name Wailua (Hawaiian: “Two Waters”) probably refers also to the north fork that joins the main stream about 2 miles (3 km) from the coast. The riverbanks are a tangle of luxuriant vegetation, and 4 miles (6 km) upstream, at the end of boat navigation, is the Fern Grotto, a scenic lava cave festooned with ferns and curtained by a small waterfall. Ruined heiaus (ceremonial and religious structures) are in evidence in the area, and one, Holoholoku (which includes a large birth stone, on which queens gave birth in order to ensure the royal status of their children), has been restored by the Bishop Museum.