Hāmākua is a district on the northeast coast of Hawaiʻi's Big Island, administered by the County of Hawaiʻi in the state of Hawaiʻi. It is also the name given for the coastline in the region, the "Hāmākua Coast".
Hāmākua's coast is approximately 50 miles (80 km) long, along the Pacific Ocean around 19°59′36″N 155°14′25″W / 19.99333°N 155.24028°WCoordinates: 19°59′36″N 155°14′25″W / 19.99333°N 155.24028°W, ending at Waipiʻo Valley and the uninhabited Waimanu Valley. The term Hāmākua Coast is used loosely to describe the region between Hilo and Waipiʻo, although the modern Hāmākua zoning district begins north of Laupāhoehoe and west of ʻŌʻōkala. The rainfall due to the prevailing northeasterly tropical trade winds produces steep erosional valleys and cliffs, showing evidence of frequent landslides. The lush vegetation and lack of sandy beaches contrasts sharply with other regions of the island.
The dominating geographic feature in Hāmākua is the volcanic mountain Mauna Kea. The district stretches south through the central plateau to the summit of Mauna Loa. Hāmākua was one of the six traditional districts of the island in ancient Hawaii (known as moku). To the north beyond Waipiʻo Valley is the Kohala district, with the older volcano Kohala mountain. According to Hui Mālama i ke Ala ʻŪlili, Hāmākua is known for its "steep mountain trails."