The Waiapu River is a river in the Gisborne District of the North Island of New Zealand, with a total length of approximately 130 kilometres (81 mi). Found in the north-east of the Waiapu Valley, it flows north-east from the joining of the Mata River and the Tapuaeroa River (both of which flow from the Raukumara Ranges), then passes by Ruatoria before reaching the Pacific Ocean at Rangitukia. Other tributaries of the Waiapu River include the , Poroporo, , Maraehara rivers, and the . It is the most well known river in the region, and lies within the rohe (territory) of Ngāti Porou, the largest iwi (extended kinship group or tribe) on the East Coast, and second largest in New Zealand. The area was the site of hostilities during the New Zealand Wars from June to October in 1865, both between