The Ruamāhanga River, Wairarapa's largest, originates from the Tararua Ranges and flows through all its townships, ending at Lake Ōnoke. Significant to mana whenua and boasting a rich history, it was named by Haunui-a-na-naia after an encounter with two birds trapped in a tree fork, leading to the name 'the two forks of the tree'. A sacred spot by the river near Lake Wairarapa, known as whare kōhanga, was where babies' placentas were buried, and orioiri, special songs of lineage, were composed for notable children.