Ruatapu is a small town in the Westland District in the West Coast region of the South Island of New Zealand. The town's name stems from Ruatapu, a figure in Māori mythology. The town is located on a narrow strip of land between the Tasman Sea and Lake Mahinapua, a shallow lake that was originally a coastal lagoon. State Highway 6 runs through Ruatapu, connecting it to the nearby towns of Hokitika and Ross. The town's economy is based upon agriculture, as well as a large sawmill, operated by Westco Lagan, which mills Radiata Pine for further processing in Christchurch.