Until the construction of the Koné-Tiwaka transverse road, the Houaïlou river valley was the only crossing route from Nouméa and Bourail on the west coast to the east coast via the Roussettes pass. The eponymous village is located at the mouth of the Houaïlou river, which is partially shown in this aerial view. Located on the eastern slope of Grande-Terre, this coastal river has its source in the Mé Maoya. It has a watershed of 211sqmi (340km2) - the 3rd of the island - and an average flow of 16ft3/s (5m3/s).