 Hāmākua's coast is approximately long, along the Pacific Ocean around , ending at Waipio Valley and the uninhabited Waimanu Valley.The term Hāmākua Coast is used loosely to describe the region between Hilo and Waipio, although the modern Hāmākua zoning district begins north of Laupāhoehoe and west of Ōōkala.The rainfall due to the prevailing northeasterly tropical trade winds produces steep erosional valleys and cliffs, showing evidence of frequent landslides.