the pelorus river was originally known as te hoeire by local māori after the first canoe to travel to the south island. the river flows east until it enters pelorus sound at havelock. the valley was the site of a massacre of ngāti kuia and ngāti apa ki te rā tō by te rauparaha. european exploration and exploitation was begun by lieutenant chetwode of in 1838, who named both the river and the sound after his vessel.